Tag: Birds (pet; ornamental; prey e.g. falcons)

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Stress bites! Researchers study mosquito/bird interactions

Research shows stressed-out birds more attractive to mosquitoes, raising fears birds exposed to stressors such as road noise, pesticides and light pollution, will be bitten more often and spread more West Nile virus

When researchers from the University of South Florida (USF) and colleagues investigated how the stress hormone, corticosterone, affects how birds cope with West Nile virus, they found that birds with higher levels of stress hormone were twice as likely to be bitten by mosquitoes that transmit the virus. Their studies have implications for the transmission of other viruses such as Eastern Equine Encephalitis, and perhaps even Zika, both known to be carried by the kind of mosquitoes used in this study. A paper describing their research was published in the Proceedings of the Royal Society B.

“Few studies have considered how stress hormone effects on individuals might influence population dynamics,” said study lead author Dr. Stephanie Gervasi, who conducted the studies while carrying out her postdoctoral work at USF and is now at the Monell Chemical Senses Center in Philadelphia. “For vector-borne diseases such as West Nile virus, the presence of corticosterone could influence pathogen spread through effects on contact rates with the mosquitoes that transmit it. In addition, stress hormones have negative effects on animals including immunosuppression and increased susceptibility to infections, which is why we are now also studying how corticosterone affects the birds’ immune response to the virus.”

According to the researchers, mosquitoes use a variety of cues to locate a target, including carbon dioxide output, body size and temperature. They hypothesized that these signals coming from a bird could convey information about stress hormones making the birds more appealing targets for the insects.

With the effects of corticosterone on mosquito feeding choices unknown, in a series of studies the researchers experimentally manipulated songbird stress hormones levels. Then they examined mosquito feeding preferences, feeding success and productivity as well as the defensive behaviors of birds trying to avoid being bitten.

In several phases of the study, zebra finches were treated with a low or high level of corticosterone and their caged light environment was altered to simulate dusk as the birds were made available to mosquitoes for measured periods of time. Bird and mosquito behavior was observed via video and the mosquitoes were later examined to determine if they had fed on the birds. The researchers also investigated the timing of subsequent mosquito egg-laying after the insects fed on the birds.

“Mosquitoes seem to be able to ‘sniff out’ the stress hormone and key in on individual birds,” said the study’s principal investigator Dr. Lynn Martin, associate professor in the USF Department of Integrative Biology. “The birds injected with higher levels of the hormone were twice as likely to be bitten by mosquitoes, even those hormone-treated birds were much more defensive than untreated ones. Corticosterone treatment increased tail flicks, and head shakes, and other defensive behaviors, but the mosquitoes managed to breach those defenses and feed more on stress hormone-treated birds.”

The study’s broader ecological implications suggest that an elevated stress hormone concentration raises the level of host attractiveness, potentially affecting the transmission of mosquito-borne diseases in a number of ways.

“Stress hormones also altered the relationship between the timing of laying and clutch size in mosquitoes,” said co-principal investigator Dr. Thomas Unnasch, chair and Distinguished USF Health Professor in the Department of Global Health, USF College of Public Health.

Mosquitoes that fed on birds with high stress hormone levels tended to lay different sized clutches of eggs at different rates than mosquitoes fed on control birds. These effects of bird stress on mosquito reproduction suggest that mosquito-feeding choice might also affect disease cycles in nature by changing the number of newborn mosquitoes that could be infected later by stressed birds.

The researchers concluded that the corticosterone levels in their test birds were within the range of normal for birds in the wild when exposed to stressors in natural their environments, such as road noise, pesticides and light pollution.

“Much more work is necessary to further understand on the interplay of host corticosterone, vector-feeding behavior, host defenses and mosquito productivity,” the researchers said.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160810084631.htm Original web page at Science Daily

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Songbirds’ epic migrations connected to a small cluster of genes

Scientists from the University of British Columbia have shown that there is a genetic basis to the migratory routes flown by songbirds, and have narrowed in on a relatively small cluster of genes that may govern the behaviour.

“It’s amazing that the routes and timing of such complex behaviour could be genetically determined and associated with a very small portion of the genome,” said researcher Kira Delmore, lead author of the paper published in Current Biology.

“What’s even more amazing is that differences in this behaviour could be helping to maintain the huge diversity of songbirds we see in the natural world.”

Seasonal migration is one of the most remarkable biological phenomena in the world, with routes spanning thousands of kilometres and involving billions of animals. Songbirds travel up to 15,000 kilometres, despite often weighing under ten grams. They undertake these journeys alone at night and return to the same locations year after year.

Delmore and her colleagues used coin-sized light-level geolocators to track songbirds’ migrations, and next-generation sequencing techniques to get an in-depth view of their genomes. They applied these two recently-developed techniques to two closely related groups of Swainson’s thrushes in B.C., and their hybrids.

While the groups are evolutionarily and genetically related, they take different routes on migration each year. A coastal group migrates down the west coast, southward to Mexico and Central America, while an inland group near Kamloops migrates southeastward to the southeastern USA and then South America. The groups interbreed northeast of Vancouver, in the coastal mountains.

Previous work conducted by the team showed that birds from the hybrid population take intermediary migration routes, which cross deserts and mountainous regions. These inferior routes likely cause hybrids to have lower reproductive success, resulting in less gene flow between the groups and more differentiation between them.

By linking the migratory behavior of hybrids to their genetic makeup, these researchers pinpointed a single cluster of roughly 60 genes on one chromosome that largely accounts for the difference in migration patterns.

The genes play an important role in the birds’ circadian, nervous and cell signalling systems. They are also located in regions of the genome that have reduced movement of genes from one population of thrushes to the other.

“Smaller scale studies have associated some genes in this region with migratory behavior in organisms as diverse as butterflies, fish and other birds,” said UBC zoologist Darren Irwin, senior author of the study. “These results provide even stronger evidence that evolution of this genetic cluster can cause different migratory routes, facilitating the evolution of two species from one.”

Delmore conducted the research while at UBC and is now with the Max Planck Institute for Evolutionary Biology, where she will continue to winnow down the set of genes responsible for migration, and use the same cutting edge techniques to investigate other populations of birds.

https://www.sciencedaily.com/ Sciencè Daily

https://www.sciencedaily.com/releases/2016/07/160728143251.htm Original web page at Science Daily

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How birds soar to great heights

Migratory birds often use warm, rising atmospheric currents to gain height with little energy expenditure when flying over long distances.

It’s a behavior known as thermal soaring that requires complex decision-making within the turbulent environment of a rising column of warm air from the sun baked surface of the earth.

But exactly how birds navigate within this ever-changing environment to optimize their thermal soaring was unknown until a team of physicists and biologists at the University of California San Diego took an exacting computational look at the problem.

In this week’s online version of the journal Proceedings of the National Academy of Sciences, the scientists demonstrated with mathematical models how glider pilots might be able to soar more efficiently by adopting the learning strategies that birds use to navigate their way through thermals.

“Relatively little is known about the navigation strategies used by birds to cope with these challenging conditions, mainly because past computational research examined soaring in unrealistically simplified situations,” explained Massimo Vergassola, a professor of physics at UC San Diego.

To tackle the problem, he and his colleagues, including Terrence Sejnowski, a professor of neurobiology at the Salk Institute and UC San Diego, combined numerical simulations of atmospheric flow with “reinforcement learning algorithms” — equations originally developed to model the behavior and improved performance of animals learning a new task. Those algorithms were developed in a manner that trained a glider to navigate complex turbulent environments based on feedback on the glider’s soaring performance.

According to Sejnowski, the “reinforcement learning architecture” was the same as that used by Google’s DeepMind AlphaGo program, which made headlines in 2016 after beating the human professional Go player Lee Sedol.

When applying it to soaring performance, the researchers took into account the bank angle and the angle of attack of the glider’s wings as well as how the temperature variations within the thermal impacted vertical velocity.

“By sensing two environmental cues — vertical wind acceleration and torque — the glider is able to climb and stay within the thermal core, where the lift is typically the largest, resulting in improved soaring performance, even in the presence of strong turbulent fluctuations,” said Vergassola. “As turbulent levels rise, the glider can avoid losing height by adopting increasingly conservative, risk-averse flight strategies, such as continuing along the same path rather than turning.”

The researchers write in their paper that, based on their study, “torque and vertical accelerations” appear to be the sensorimotor cues that most effectively guide the most efficient soaring path of birds through thermals, rather than differences in temperature.

“Temperature was specifically shown to yield minor gains,” they write adding that “a sensor of temperature could then be safely spared in the instrumentation for autonomous flying vehicles.”

“Our findings shed light on the decision-making processes that birds might use to successfully navigate thermals in turbulent environments,” said Vergassola. “This information could guide the design of simple mechanical instrumentation that would allow autonomous gliders to travel long distances with minimal energy consumption.”

“The high levels of soaring performance demonstrated in simulated turbulence could lead to the development of energy efficient autonomous gliders,” said Sejnowski, who is also a Howard Hughes Medical Institute Investigator.

Other members of the research team were Gautam Reddy, a physicist at UC San Diego and the first author of the paper, and Antonio Celani of the Abdus Salam International Center for Theoretical Physics in Trieste, Italy. The study was supported by a grant from the Simons Foundation.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/08/160801163844.htm  Original web page at Science Daily

 

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Shorter telomeres reveal stress in migratory birds

The stress of birds’ continent-spanning annual migrations, it appears, leads to faster aging and a potentially earlier death. A new study in The Auk: Ornithological Advances reveals that telomeres, structures on the ends of chromosomes that shorten with age, are shorter in migratory birds than in their non-migratory counterparts.

Migration lets birds take advantage of abundant food resources at high latitudes during the breeding season while escaping the region’s harsh winters. However, it’s also an enormous undertaking, and the benefits that birds gain from it come with a cost. Carolyn Bauer of North Dakota State University and her colleagues compared the telomeres — bits of non-coding DNA that shorten during cell division and stress — of migratory and resident birds from the same species, the Dark-eyed Junco. They found that the migrants had significantly shorter telomeres than birds that stayed put year-round, suggesting that the migratory birds were aging at a faster rate and that the stress of a migratory lifestyle may actually shorten birds’ lifespans.

“Whenever our cells divide, we lose a little bit of DNA on the ends of our chromosomes, and telomeres are simply non-coding regions that act as ‘protective caps,” explains Bauer. Once they reach a certain threshold of shortness, the cell dies. Importantly, exposure to stress can also make telomeres shorten faster. For their study, Bauer and her colleagues collected blood samples from 11 migratory and 21 resident juncos in Virginia, using only first-year birds to ensure that any telomere differences were not simply due to age. “I’ve been interested in measuring telomeres since I was undergraduate at the University of Washington,” says Bauer. “I remember my introductory biology professor lecturing about telomeres and how environmental stress could cause them to shorten.”

If migrating is so stressful, why keep doing it? Bauer and her colleagues believe that the costs of migration must be balanced out by the reproductive boost birds get from nesting in resource-rich northern habitats. They hope that future studies will determine whether shorter telomeres reflect the stress of migration itself or if they’re the result of decreased self-maintenance, as well as whether telomere length is negatively correlated with migratory distance.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/08/160803072812.htm Original web page at Science Daily

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How birds unlock their super-sense, ultraviolet vision

The ability of finches, sparrows, and many other birds to see a visual world hidden to us is explained in a study published in the journal eLife.

Birds can be divided into those that can see ultraviolet (UV) light and those that cannot. Those that can live in a sensory world apart, able to transmit and receive signals between each other in a way that is invisible to many other species. How they unlock this extra dimension to their sight is revealed in new findings from the Washington University School of Medicine in St. Louis.

The study reveals two essential adaptions that enable birds to expand their vision into the UV range: chemical changes in light-filtering pigments called carotenoids and the tuning of light-sensitive proteins called opsins.

Birds acquire carotenoids through their diets and process them in a variety of ways to shift their light absorption toward longer or shorter wavelengths. The researchers characterized the carotenoid pigments from birds with violet vision and from those with UV vision and used computational models to see how the pigments affect the number of colors they can see.

“There are two types of light-sensitive cells, called photoreceptors, in the eye: rods and cones. Cone photoreceptors are responsible for color vision. While humans have blue, green, and red-sensitive cones only, birds have a fourth cone type which is either violet or UV-sensitive, depending on the species,” says senior author Joseph Corbo, MD, PhD, Associate Professor of Pathology and Immunology.

“Our approach showed that blue-cone sensitivity is fine-tuned through a change in the chemical structure of carotenoid pigments within the photoreceptor, allowing both violet and UV-sighted birds to maximize how many colors they can see.”

The study also revealed that sensitivity of the violet/UV cone and the blue cone in birds must move in sync to allow for optimum vision. Among bird species, there is a strong relationship between the light sensitivity of opsins within the violet/UV cone and mechanisms within the blue cone, which coordinate to ensure even UV vision.

Taken together, these results suggest that both blue and violet cone cells have adapted during evolution to enhance color vision in birds.

“The majority of bird species rely on vision as their primary sense, and color discrimination plays a crucial role in their essential behaviors, such as choosing mates and foraging for food. This explains why birds have evolved one of the most richly endowed color vision systems among vertebrates,” says first author Matthew Toomey, a postdoctoral fellow at the Washington University School of Medicine.

“The precise coordination of sensitivity and filtering in the visual system may, for example, help female birds discriminate very fine differences in the elaborate coloration of their suitors and choose the fittest mates. This refinement of visual sensitivity could also facilitate the search for hidden seeds, fruits, and other food items in the environment.”

The team now plans to investigate the underlying molecular mechanisms that help modify the carotenoid pigments and light-sensitive protein tuning in a wide range of bird species, to gather further insights into the evolution of UV vision.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160712093355.htm  Original web page at Science Daily

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Scavenger crows provide public service, research shows

Crows are performing a useful function and keeping our environment free from rotting carcasses, research carried out at the University of Exeter in Cornwall has discovered.

Using motion activated cameras in and around Falmouth and the University’s Penryn Campus, Cornwall, ecologists observed what happened to experimental rat carcasses which they placed under view.

The researchers found that most of the carcass removal ecosystem service — which has been well studied in more natural and exotic habitats, such as vultures in Africa — is being carried out by crows, with a little help from foxes, magpies, badgers and herring gulls.

Dr Richard Inger, a researcher attached to the Environmental and Sustainability Institute at Penryn Campus, said: “If you consider all the wildlife that lives in the habitats in our towns and countryside, it might seem odd that we rarely see dead animals, apart from roadkill. This is because other animals act as scavengers and eat them.

“It’s a bit grizzly but crows and other scavengers, which are often perceived as pests and generally fairly unloved species, are performing a very valuable service. Without these scavengers dead animals would be scattered around our environment rotting and causing a hygiene hazard.”

The researchers observed and filmed 17 vertebrate species eating rat carcasses which they placed at 12 study sites between May and September 2015. Seven species including the Carrion Crow, the Common Buzzard, European Magpie, Herring Gull, Fox and Badger were recorded eating the carcasses, with 98 per cent of the activity carried out by the Crows.

Dr Inger highlighted the importance of the scavenger role and added: “We know what can happen when natural scavengers are removed as this was the case with the vulture populations of India, which plummeted massively in the 1990s. Vultures were fatally poisoned by a veterinary drug given to cattle, meaning that carcasses were not eaten by vultures but instead by feral dogs, which grew in numbers and caused a huge increase in cases of rabies.”

Professor Kevin J.Gaston, Director of the Environment and Sustainability Institute, and co-author on the paper, said: “It is vital that we understand the different ecological functions and services that organisms provide, if we are to value and manage them most appropriately. Sometimes, as in this case, it will be individual species that are especially important. In others it will be the diversity of species. In both cases, the level of function and service depends on having sufficient individuals thriving in the landscape.”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/07/160712110430.htm Original web page at Science Daily

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Ravens learn best from their affiliates

Transmission of information from one individual to another forms the basis of long-term traditions and culture, and is critical in adjusting to changing environmental conditions. Animals frequently observe each other to learn about food, predators and their social environment. The study fills an important gap in our understanding of how different types of social connections affect animals’ ability to learn from the behavior of others.

Social connections range from aggressive interactions to the affiliative behaviors that are critical in forming strong social bonds. Human social behavior is frequently analyzed as social networks to capture its extent and complexity. By adopting a similar approach for ravens and analyzing their social networks, Christine Schwab and Thomas Bugnyar found that not all social connections are equally effective at influencing observation and learning. In particular, networks based on affiliative behaviors (sitting close to and preening each other, sharing food and objects) played a major role in influencing how information was transmitted in the group. Some of the most frequent affiliative behaviors were between siblings, thus emphasizing the importance of family ties in learning.

Previous studies have shown that physical proximity between individuals can facilitate learning. However, until now, hardly anything was known about the role of different social connections in observation and learning. To mimic the presence of novel information, the researchers gave raven groups a task with which they were unfamiliar. The task included a food reward to motivate ravens to solve it. Ravens only observed others’ interactions with the task if they had strong social bonds to those group members. Presence of strong social bonds increases tolerance among individuals, allowing them to observe each other from a close distance. Birds with strong bonds to the group members who had already solved the task were able to observe them from a close distance, and as a result, gained this new information sooner than those who were not connected.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160713101619.htm  Original web page at Science Daily

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* Newborn ducklings can acquire notions of ‘same’ and ‘different’

Scientists from the University of Oxford have shown that newly hatched ducklings can readily acquire the concepts of ‘same’ and ‘different’ — an ability previously known only in highly intelligent animals such as apes, crows and parrots.

Ducklings and other young animals normally learn to identify and follow their mother through a type of learning called imprinting, which can occur in as little as 15 minutes after hatching. Imprinting is a powerful form of learning that can allow ducklings to follow any moving object, provided they see it within the species’ typical ‘sensitive period’ for imprinting.

In this new study, published in the journal Science, ducklings were initially presented with a pair of objects either the same as or different from each other — in shape or in colour — which moved in a circular path.

The ducklings therefore ‘imprinted’ on these pairs of moving objects before being tested for their preferences between different sets of objects. In these subsequent choice tests, each duckling was allowed to follow either of two pairs of objects composed of shapes or colours to which the duckling had not previously been exposed.

For example, if an individual duckling had originally been exposed to a pair of spherical objects, in the choice test it may have had to choose between following a pair of pyramids (same) or a pair made up of one cube and one cuboid (different).

If the birds had learned the relationship between members of the original moving pair, then they should have followed the pairs of novel objects showing that same relationship (either ‘same’ or ‘different’), even if they had never seen the test objects.

In the example above, ducklings that had been imprinted on two spheres should have followed the set of two pyramids, because they were the same as each other. This is exactly what the ducklings did.

About three-quarters of the ducklings preferred to follow the stimulus pair exhibiting the relationship they had learned in imprinting, and their accuracy was as good whether they had to learn the concept of equal or different, or whether they were tested with shapes or colours.

Professor Alex Kacelnik of Oxford University’s Department of Zoology, who has worked extensively on learning and decision-making in animals, said: ‘To our knowledge this is the first demonstration of a non-human organism learning to discriminate between abstract relational concepts without any reinforcement training. The other animals that have demonstrated this ability have all done so by being repeatedly rewarded for correct performance, while our ducklings did it spontaneously, thanks to their predisposition to imprint when very young.

‘And because imprinting happens so quickly, the ducklings learned to discriminate relational concepts much faster than other species, and with a similar level of precision.’

Antone Martinho, a doctoral student in Oxford’s Department of Zoology and the study’s first author, said: ‘While it seems surprising at first that these one-day-old ducklings can learn something that normally only very intelligent species can do, it also makes biological sense. When a duckling is young, it needs to be able to stay near its mother for protection, and an error in identifying her could be fatal.

‘Ducks walk, swim and fly, and are constantly changing their exact shape and appearance as they extend their wings or become partially submerged, or even change angle with respect to the viewer. If the ducklings just had a visual “snapshot” of their mother, they would lose her. They need to be able to flexibly and reliably identify her, and a library of concepts and characteristics describing her is a much more efficient way to do so, compared with a visual memory of every possible configuration of the mother and her environment.

‘Still, this is an unexpected feat for a duckling, and a further reminder that “bird-brain” is quite an unfair slur.’

The discovery of relational concept learning in a new species and in a newly hatched baby bird suggests that this ability may not be as rare or as difficult as previously thought.

Professor Kacelnik added: ‘It may mean that relational concepts are adaptively useful or even necessary to a wider variety of animal. Most animals will, like the ducklings, need identification mechanisms that are robust to natural variation. A challenge we face now is to identify the processes by which the animals’ brains achieve it.’

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/07/160714151856.htm  Original web page at Science Daily

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Urban bird species risk dying prematurely due to stress

Birds of the species Parus Major (great tit) living in an urban environment are at greater risk of dying young than great tits living outside cities. Research results from Lund University in Sweden show that urban great tits have shorter telomeres than others of their own species living in rural areas. According to the researchers, the induced stress that the urban great tits are experiencing is what results in shorter telomeres and thereby increases their risk of dying young.

Telomeres are located at the end of each DNA strand in the body’s chromosomes, in both great tits and humans. The length of the telomeres can be described as a kind of age biomarker — short telomeres mean short life expectancy. According to the researchers, their study shows that the environment in which great tits grow up determines the length of their telomeres more than their genetics.

“Although there are advantages to living in cities, such as the access to food, they seem to be outweighed by the disadvantages, such as stress — at least in terms of how quickly the cells of the great tits age,” says biologist Pablo Salmón who conducts research in the field of evolutionary ecology at the Faculty of Science, Lund University.

The researchers obtained the results by studying great tit groups of siblings. Half of the siblings grew up in the countryside, half in Malmö. After 13 days, blood was taken to measure the length of their red cell telomeres. Pablo Salmón and his colleagues had partly anticipated the outcome, but were still surprised when they saw how big the difference in the length of the telomeres was after only 13 days.

“Previous studies have shown that genetics have an effect on the telomere length in individual birds. What we’re showing now is that growing up in a stressful environment has even more of an impact,” he says.

The study, which he conducted together with colleagues at the Faculty of Science, indicates the need for further studies to better understand how people can help birds in urban environments live longer.

“The impact that urbanisation has on wildlife must be studied much more, or we won’t be able to understand the threats that birds are exposed to in urban environments, and won’t be able to do anything about them. Our results also raise questions concerning the aging of other animals affected by urbanisation, and humans for that matter,” says Pablo Salmón. The study is published in an article in the scientific journal The Royal Society Journal Biology Letters.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160620112028.htm  Original web page at Science Daily

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* Droppings activate the immune system in nestlings

Until now, it was believed that birds removed droppings from their nests to avoid the appearance of parasites. A recent investigation contradicts this hypothesis, concluding that feces activate the immune system of blackbird chicks and only attract insects.

In the animal world, strict rules are followed to deal with sources of contamination and potential dangers such as predation. In the case of birds, parents remove their chicks’ droppings from the nest on a daily basis to conserve hygiene. A new study carried out in Spain and published in the journal Frontiers in Zoology demonstrates that the presence of feces in nests attracts insects and provokes the activation of nestlings’ immune systems. This provides important information on the reason for this sanitation behaviour.

Until now, the predominant hypothesis in ornithology (the branch of zoology dedicated to the study of birds) was that birds removed droppings from the nest in order to avoid attracting parasite species to the nest. However, the new research refutes this. “Our study demonstrates that parasites being attracted by feces does not appear to be the reason for which evolution has favoured this behaviour, despite this having been traditionally assumed to be the case,” Juan Diego Ibáñez-Álamo said, the paper’s main author and an investigator at the Spanish National Scientific Research Council’s (CSIC) Doñana Biological Station and at the University of Groningen (Netherlands).

The scientists ran three different experiments using insect traps, artificial nests and real blackbird nests in order to observe the attractant effect of droppings on parasites.

Although the experimental predictions were for a higher quantity of parasites when feces were present, “the fecal sacs did not attract a higher number of parasites,” says the researcher.

The chicks’ immune systems were affected by the presence of feces; specifically, there was a change in the ratio of heterophils to lymphocytes (blood cells that fight against pathogens such as parasites), a physiological indicator of birds’ response to stress. “This ratio was significantly higher in nestlings that lived near the fecal sacs than in those which did not have feces near them,” state the authors. The scientists also observed that the chicks’ droppings caused an increase in the appearance of flies and a reduction in the number of acarids. The authors indicate the capacity of flies to act as vectors for the transmission of damaging microorganisms as a cause of immune system activation.

Nestlings produce feces enclosed in a mucous covering. This unique structure, shown in a previous study to function as isolation against bacteria, may also be responsible for preventing parasites being attracted to the nest. “It is possible that the mucus acts as a barrier, blocking the spread of chemical signals that parasites may use to locate the chicks,” says Ibáñez-Álamo. “The findings of our study appear to indicate that microorganisms may play a very significant role in relation to the cleanliness of birds’ nests,” he adds.

Even so, the authors consider this habit of parent birds to be the result of several factors: “We cannot rule out that parental behaviour may be altered by the presence of feces near the nest,” they state. Even predation could be another determinant cause for this behaviour.

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/06/160621095548.htm Original web page at Science Daily

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To tool or not to tool? Clever cockatoos make economic decisions about tool use

As animal tool use events are extremely rare, is often quickly rated as intelligent. Nevertheless, some types of tool use can be controlled by much simpler processes that are a part of the respective animal’s inborn behavioural repertoire. Intelligent tool use requires the ability to flexibly adapt a behaviour to changing environmental situations. The Indonesian Goffin’s cockatoo has even the rare capacity to use two different types of tools (sticks for probing and raking food into reach as well dropping stones/balls into tubes to knock out a reward inside). The same birds also previously showed a solid performance in the classic “marshmallow” experiment from human psychology: They controlled their impulse to consume an immediate lower quality food item in the prospect of gaining a better food type after a time delay.

Isabelle Laumer, Alice Auersperg und Thomas Bugnyar from the University of Vienna and the Veterinary University of Vienna now investigate flexibility in tool related decision-making in the Goffin’s cockatoo. Two different types of food items were used: Cashew nut which is their favourite food type and Pecan nut which the birds like but disregard if cashew nut is available as well. The also used two types of apparatuses containing a food item which was temporarily out-of-reach and two types of tools: an apparatus which is only operable by probing with a stick tool but not by dropping a ball inside and an apparatus which could only be operated by dropping a ball inside but not by probing with a stick. During testing, an apparatus was placed on a table and a choice between two items (usually a food item and a tool) was offered alongside. Once birds had picked one item the other was immediately removed.

Interestingly, the cockatoos flexibly adapted their decisions to different situations. “If a lower value food or a high value food was out-of-reach inside the apparatus and the choice was between a high value food item and a tool, they chose the food over the tool, even when the tool was functional for the apparatus,” explains Isabelle Laumer who conducted the study as part of her PhD thesis. “However, when the cockatoos could decide between the lower value food and a tool they choose the tool but only provided that it worked for the available apparatus: For example when the stick and the lower value food was available but the ball apparatus was on the table they chose the low value food over the tool. When the stick apparatus with the high value food inside was available they chose the stick tool over the immediate lower value food,” she further elaborates.

Nevertheless, the birds’ ability to solve the problem stopped when both apparatuses were offered at the same time each bearing a different food type and the decision was between the both tools. In the latter case researchers believe that the animals may have hit a limit in working memory capacity due to the amount of task components involved.

“Our findings parallel previous results in primates: the cockatoos could overcome immediate impulses in favor of future gains even if this implied tool use. Beyond that we additionally found that they at same time attended to the functionality of the available tool in the present contex,” says Alice Auersperg, Head of the Goffin Lab in Austria. She continues: “As wild Goffin cockatoos are unlikely to be specialized on tool use, this shows that tool related decision-making can arise from relatively general modes of cognitive processing as, for example a combination of flexibility, sensorimotor and impulse control.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160623100912.htm Original web page at Science Daily

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Female blue tits sing in the face of danger

Until now, the singing behaviour of songbirds had been mainly associated with competitive behaviour and the search for a partner. Moreover, males had long been considered to be the more active singer. Females were compared to the behaviour of the males and were seen as relatively “lazy” with regard to singing.

These assumptions had also been applied to one of the most prominent local songbirds, namely, the blue tit. But female blue tits, like males, also display a variety of vocal patterns. This suggests that vocalization is not limited exclusively to courtship or competition.

Herbert Hoi and Katharina Mahr of the Konrad Lorenz Institute of Ethology at Vetmeduni Vienna have demonstrated for the first time that female blue tits sing in the presence of a predator.

Vocalization did not serve as an alarm, however, nor was it limited to females. The researchers used stuffed dummies of two predatory types in order to provoke a reaction from the birds. “We presented the nest of blue tits either with a stuffed sparrow hawk, a bird of prey, or an Aesculapian snake and analysed the reactions mainly of female blue tits. We already knew that songbird males sometimes respond to threats by singing,” said Hoi.

The team from Vetmeduni Vienna, together with Carlo Seifert of the University of South Bohemia, for the first time documented vocalizations of female songbirds in danger situations. Their song strongly resembled that of the males also present in the simulated predation event. Both sexes, however, reacted only to the threat from the bird of prey and not the snake. The sparrow hawk is considered to be a danger to adults, while the snake is a threat to nestlings that can be more easily driven from the nest.

It is interesting that the blue tits react to the threat by singing. One would assume that singing attracts more attention. “The animals may be indicating a heightened ability to escape. They show the predator that they have seen it and can flee at any time,” Hoi says. Song could also be a sign of physiological stress or encouragement

Hoi believes there could be another, for people easily understandable, explanation. The presence of a predator is very stressful. The singing behaviour could therefore simply be an endocrinological response of the body or, to quote Konrad Lorenz, a “displacement activity.”

The researchers were able to exclude the possibility that the females were sending a distress call. In several cases, the male was present during the event. And both would then sing together. The researchers see the joint singing as a way for the pair to encourage each other and to strengthen the pair bond.

The scientists still see the need for future research in order to better understand the singing behaviour of songbirds. “Our work confirms the assumption that females use their singing in more ways than just choosing their partner or defending their territory. But more studies will be needed in order to better interpret the different vocalization patterns,” Hoi believes.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/06/160624100810.htm  Original web page at Science Daily

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World’s first successful artificial insemination of southern rockhopper penguin

DNA tests have confirmed that one of the three southern rockhopper penguin chicks born at Osaka Aquarium Kaiyukan between June 4 and 6 was conceived through artificial insemination. This is the result of a project led by Kaiyukan with the collaboration of Associate Professor KUSUNOKI Hiroshi (Kobe University Graduate School of Agricultural Science). It is the world’s first successful case of a southern rockhopper penguin being conceived through artificial insemination.

Southern rockhopper penguins are a species of birds approximately 50cm in height which inhabit southern islands near Antarctica such as the Falkland Islands. They are on the red list of the International Union for Conservation of Nature as a threatened species.

Kaiyukan and Associate Professor Kusunoki began their joint research in 2011, aiming to elucidate the breeding habits of southern rockhopper penguins and develop the technology for their artificial insemination. In spring 2015 the group obtained a fertilized egg, but the chick did not hatch, and DNA tests determined that the unborn chick was the result of natural reproduction.

This time multiple penguins were selected for breeding, and the group enlisted the cooperation of Tokyo Sea Life Park, where scientists had previously succeeded in breeding species through natural reproduction. At the end of April they obtained a healthy sperm sample from a male penguin at Tokyo Sea Life Park and transported it to Kaiyukan without loss of quality. At Kaiyukan they used blood tests to estimate the laying days of three female penguins and determine the best timing for artificial insemination.

Between April 28 and May 4 the three female penguins laid five eggs between them. These were incubated by the penguin couples for approximately one month, and three chicks hatched between June 4 and 6. Results of DNA tests carried out on blood samples taken from inside the eggshells revealed that one of these chicks was conceived through artificial insemination.

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https://www.sciencedaily.com/releases/2016/06/160628072251.htm  Original web page at Science Daily

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‘Baby talk’ can help songbirds learn their tunes

Adult songbirds modify their vocalizations when singing to juveniles in the same way that humans alter their speech when talking to babies. The resulting brain activity in young birds could shed light on speech learning and certain developmental disorders in humans, according to a study by McGill University researchers.

Lead author Jon Sakata, a professor of neurobiology at McGill, says that songbirds learn vocalizations like humans learn speech. “Songbirds first listen to and memorize the sound of adult songs and then undergo a period of vocal practice-in essence, babbling-to master the production of song.”

Researchers have been studying song learning in birds for some time. But the degree to which social interaction with adult birds contributes to that learning has been unclear. That’s because, unlike this current work, past studies didn’t control for the time exposed to song and the presence of other birds.

In this study, published in the journal Proceedings of the National Academy of Sciences, a group of juvenile zebra finches was allowed to interact with an adult. Another group simply heard adult songs played through a speaker. After a brief period of “tutoring” the juveniles were house individually for months as they practiced their tunes.

Sakata and his team found that avian pupils who socialized with an adult learned the adult’s song much better. That was true even if the social tutoring lasted just one day. In analyzing why this would be so, Sakata and his team made a surprising discovery.

Adult zebra finches change their vocalizations when singing to juveniles. Sakata says just as people speak more slowly and repeat words more often when speaking to infants, so do these birds. “We found that adult zebra finches similarly slow down their song by increasing the interval between song phrases and repeat individual song elements more often when singing to juveniles.”

What’s more, the researchers found that juvenile birds pay more attention to this “baby talk” compared to other songs. And the more the juveniles paid attention, the better they learned.

The researchers took their work a step further by examining the activity of certain neurons in parts of the brain associated with attention. They found that more neurons that produce the chemicals dopamine and norepinephrine were turned on after socially interacting with a singing adult than after simply hearing song through a speaker.

Dr. Sakata says this finding could have implications beyond the avian world. “Our data suggest that dysfunctions in these neurons could contribute to social and communicative disorders in humans. For example, children who suffer from autism spectrum disorders have difficulty processing social information and learning language, and these neurons might be potential targets for treating such disorders.”

Dr. Sakata is now testing whether raising dopamine and norepinephrine levels in the brain can help birds learn song when they only hear adult songs. As he puts it, “We are testing whether we can “trick” a bird’s brain into thinking that the bird is being socially tutored.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160531165239.htm Original web page at Science Daily

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Scientists identify mutation that causes muffs and beards to grow on chickens

The growth of long facial feathers, creating the appearance of muffs and beards on chickens, is caused by a chromosomal rearrangement affecting a gene involved in feather development, report Xiaoxiang Hu of the China Agricultural University in Beijing and colleagues, in a new study published on June 2 in PLOS Genetics.

Unusual plumage and fancy combs aren’t just interesting traits appreciated by poultry fanciers, but opportunities to explore the genetics underlying these striking variations. Scientists investigated the mutation that causes the Muffs and beard characteristic in certain chicken varieties by mapping the trait to the correct location on the chromosome and sequencing that region from chickens with and without Muffs and beard. They found that chickens with the Muffs and beard trait had three duplicated regions of chromosome 27, inserted next to one of the original gene regions. By examining changes in gene expression, they showed that one of the duplicated genes, HOXB8, which is known to function in feather development, was present at high levels in the facial skin of chickens with Muffs and beard, but not in regular chickens.

The scientists suspect that HOXB8 expression may extend the growth phase of the facial feathers, creating the characteristic bearded appearance. Other HOX gene members are linked to feather development, such as HOXC8, which is associated with a crest of feathers on top of the head. The findings present an excellent model for exploring the regulation of HOX genes in different parts of the body during development.

Dr. Guo says: “Muffs and beard in chicken is caused by a structural variation that consists of three duplicated regions on GGA27 and results in the ectopic expression of HOXB8 in facial skin. Our findings show the significance for structural variations on phenotypic diversity and a novel role for HOXB8 in feather formation. In future study, we’ll focus on the regulation of HOX genes in feather cycles.”

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https://www.sciencedaily.com/releases/2016/06/160602151713.htm Original web page at Science

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Shifting bird distribution indicates a changing Arctic

Shifts in the distribution of Spectacled Eiders, a predatory bird at the top of the Bering Sea’s benthic food web, indicate possible changes in the Arctic’s marine ecosystem, according to new research in The Condor: Ornithological Applications.

Matt Sexson of the USGS Alaska Science Center and his colleagues compared recent satellite telemetry data from molting eiders with data from the mid-1990s. They found that in two of the species’ four primary molting areas, the birds have shifted their range significantly in the intervening decades, and the researchers interpret this as an indicator of ecosystem change–eiders go where their prey is, and their movements could indicate big changes in the community of bottom-dwelling, cold-water-dependent invertebrates they eat.

It’s easier to track marine predators than it is to track their prey, explains Sexson. “It’s tough to speculate on the connection with climate change because the data are so sparse, but we know that the north Pacific is changing,” he says. “There’s a lot of corresponding evidence that together all says something big is happening here, and eiders provide a readily available indicator that changes are occurring.”

Sexson and his colleagues spent months at a time in the remote Arctic to catch eiders on land during their breeding season, luring them into nets before making a two-hour trek back to base camp with each bird to surgically implant a satellite transmitter. “It’s a lot of hard work, but it’s a lot of fun,” Sexson says. “I used to just flip past the eiders in bird field guides, thinking I’d never see any of these. Now five years later I’m catching them and holding them. I’ve really developed a love for this group of birds–how unique they are, how beautiful they are. I’ve just become attached.”

According to the University of Maryland’s Jackie Grebmeier, an expert on Arctic marine ecosystems who was not involved with the new study, “The results of this research provide an important finding of biological response of an upper-trophic-level seabird to climate warming and sea ice retreat, another piece in the puzzle to address ecosystem change in the Pacific Arctic region.” As Arctic water warms, whole communities of animals are moving north–and there’s only so far they can go.

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https://www.sciencedaily.com/releases/2016/06/160601082303.htm  Original web page at Science Daily

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Sparrows with unfaithful ‘wives’ care less for their young

A new study shows that male sparrows can judge if a spouse is prone to infidelity, providing less food for their brood if their partner is unfaithful.

Sparrows form pair bonds that are normally monogamous, but many females are unfaithful to their partner and have offspring with other males. Biologists believe that the male birds are unfaithful to ensure that they father as many chicks as they can, while females are unfaithful with males of better ‘genetic quality’ — ones that are fitter and could produce stronger offspring.

However, cheating comes with a cost — the cheating female’s partner will provide less food for their nest of young. It has long been suspected that males know that not all the chicks in their nest are theirs, and so make a decision to provide less. But an alternative explanation is that cheating females and lazy males tend to pair up naturally.

Researchers from the UK, Germany, and Australia have now revealed that males make the decision of how much to provide for their chicks based on the tendency of their partner to cheat. The study, published today in The American Naturalist, followed the entire sparrow population of the island of Lundy in the Bristol Channel for 12 years.

Lead researcher Dr Julia Schroeder of the Department of Life Sciences at Imperial College London said: “Males changed their behaviour based on their partner. When they switched from a faithful partner to one prone to infidelity, they provided less food for their brood.” Females might also change their behaviour when paired with a less lazy male, cheating less with a more attentive father.

The research showed that males cannot actually identify whether all the chicks in their nest are theirs or not, and instead base their feeding decisions on who their female partner is.

“If chicks were switched into a nest where the female was faithful, then the father at that nest kept up his hard work providing for the chicks, suggesting they have no mechanism, such as smell, to determine which chicks are theirs,” said Dr Schroeder. “Instead, the males may use cues from the female’s behaviour during her fertile period — for example how long she spends away from the nest.”

The study followed 200 males and 194 females as they formed 313 unique monogamous pairs and hatched 863 broods on Lundy. Some sparrow ‘divorces’ occurred — but most changes of life partner were due to a death.

The team DNA genotyped every sparrow, allowing them to build up precise family trees, and find out which females were most unfaithful and who their cheating males were. “Lundy is a unique natural laboratory because it is almost a closed system — very few birds leave the island or arrive from the mainland. In the entire 12 years only four birds immigrated to Lundy, possibly carried by boat.”

Dr Schroeder and her team are continuing to study the Lundy sparrows to uncover how and why social behaviours like monogamy arose. Being unfaithful may be a costly behaviour for females because they only lay a limited number of eggs, and it may be a hangover from when their ancestors were not monogamous, rather than a useful strategy for getting the strongest offspring.

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https://www.sciencedaily.com/releases/2016/05/160531222140.htm  Original web page at Science Daily

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Changing weather patterns threaten grassland sparrows

Two of North America’s declining grassland songbirds may be particularly vulnerable to altered weather patterns caused by climate change, according to new research in The Condor: Ornithological Applications.

Extreme heat waves have been known to kill adult birds, and droughts can cause birds to abandon nests or skip breeding altogether. To learn what species might be at greatest risk, Jessica Gorzo of the University of Wisconsin-Madison and her colleagues analyzed more than four decades of bird survey data from the Dakotas, Montana, and Wyoming, looking for patterns linking grassland bird abundance to temperature and precipitation.

Of the 14 bird species the researchers focused on, 5 showed significant associations with weather trends, their populations appearing to increase or decrease depending on whether a year had been particularly warm, cold, wet, or dry. Two, the closely related Grasshopper and Baird’s sparrows, are already declining enough to concern conservationists, and this study shows that they may be particularly vulnerable to the warmer, drier conditions that are likely becoming more frequent due to climate change.

“With climate change, there are bound to be winners and losers,” according to Gorzo. “Of the species we considered, Grasshopper and Baird’s Sparrows may be imminently at risk. These species responded similarly to our weather metrics, which made sense in light of their shared life history traits. Knowing that these species need tall, lush grassland vegetation, increasingly dry conditions could inhibit the growth they need to be successful.”

The data for the study came from the North American Breeding Bird Survey, a program for which skilled volunteer birders conduct annual bird counts along set routes. “It was really an honor to work with this dataset, because though I don’t run a route myself, I have many friends who have been visiting the same route year after year and take pride in what they contribute to our understanding of the continent’s birds,” says Gorzo. “It is a tremendous volunteer effort that takes skill, dedication and hard work. To be able to put it to good use to elucidate some patterns relevant to climate change felt really rewarding, and I can’t thank birders over the decades enough for working year in and year out to add to this dataset.”

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https://www.sciencedaily.com/releases/2016/06/160608095535.htm Original web page at Science Daily

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How do some birds get such bright red feathers?

In the bird world, the color red has special significance. Many species use red signals to attract mates or deter rivals, adding the color to their beaks, feathers, or bare skin. Generally speaking, as far as many birds are concerned, redder is better. Now, two teams of researchers have independently identified an enzyme-encoding gene that allows some bird species to convert yellow pigments from their diets into that remarkable red. Their findings are reported on May 19 in Current Biology.

“To produce red feathers, birds convert yellow dietary pigments known as carotenoids into red pigments and then deposit them in the feathers,” says Miguel Carneiro of Universidade do Porto in Portugal. “Birds also accumulate these same red pigments in one of the cone photoreceptor types in their retina to enhance color vision. We discovered a gene that codes for an enzyme that enables this yellow-to-red conversion in birds.”

“It was known that some birds have the ability to synthesize red ketocarotenoids from the yellow carotenoids that they obtain in their diet, but the gene or enzyme involved, and its anatomical location, have been obscure,” adds Nick Mundy of the University of Cambridge. “Our findings fill this gap and open up many future avenues for research on the evolution and ecology of red coloration in birds.”

Carneiro’s team, including Joseph Corbo of Washington University School of Medicine in St. Louis and Geoffrey Hill of Auburn University, made their discovery thanks to canary fanciers who crossed a yellow canary with a red siskin almost 100 years ago, producing the world’s first red canary. In the new study, the researchers compared the genome sequences of yellow and red canaries to red siskins in search of the gene responsible for the birds’ color differences.

Their search led them to a cytochrome P450 enzyme, dubbed CYP2J19. Further analysis of the gene’s expression showed that the enzyme is expressed at high levels in the skin and liver of red factor canaries, strongly implicating it as the enzyme responsible for red coloration.

In the other report, Mundy and colleagues, including Staffan Andersson of the University of Gothenburg, and Jessica Stapley of the University of Sheffield, found their way to the cytochrome P450 gene cluster through comparisons of standard zebra finches, which have a distinctive red beak, and mutant zebra finches with yellow beaks. Zebra finches have three related cytochrome P450 genes, and the researchers found multiple mutations in this genetic region in the yellowbeak birds. They further found that the enzyme was expressed in almost undetectable levels in the birds’ yellow beaks.

The genetic findings pave the way for new kinds of studies on the red coloration of birds, according to the researchers. They also raise many new and intriguing questions. For example, the gene now identified belongs to a family of genes known to play an important role in detoxification.

“In sexual selection, red color is thought to signal individual quality and one way it can do this is if the type or amount of pigmentation is related to other physiological processes, like detoxification,” Andersson says. “Our results, which link a detoxification gene to carotenoid metabolism, may shed new light on the debated honesty of carotenoid-based signals.”

Corbo says one thing that came as a particular surprise to them was the discovery that the “redness gene” is present in the genomes of many, if not most, bird species, not just those with red feathers.

“Diurnal birds appear to use this gene to produce red pigments in the retina to enhance color vision,” Corbo says. “However, only birds with red feathers additionally express the gene in their skin. These findings suggest that nearly all birds have the latent capacity to make red feathers, but in order to actually do so, they must evolve the means of expressing this gene in the skin in addition to the retina.”

Mundy and Andersson are now returning to the birds where their search for the “red-maker” once began, the African widowbirds and bishops, which show “spectacular differences among different species.” Most intriguingly, Andersson adds, “dazzling red colors have evolved repeatedly in this group, mostly by the mechanism described here, but there are some very interesting exceptions.”

Corbo and colleagues also plan to explore red feathers in many more bird species, to see whether they rely on the same or different mechanisms. They say they also will continue using the canary as a model for uncovering the genetic basis of other interesting traits in birds.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160519130102.htm  Original web page at Science Daily

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Male birds may sing, but females are faster at discriminating sounds

It may well be that only male zebra finches can sing, but the females are faster at learning to discriminate sounds. Leiden researchers publish their findings in the scientific journal Animal Behaviour.

The scientists reached this conclusion after a meta-analysis of different experiments with the songbirds. Combining the results of 14 separate studies gave them a population of 87 birds to work from. The aim of the research was to find out why some birds could recognize sounds faster than others.

The zebra finches heard one of two sound types after pecking at an LED sensor. If — after hearing the right sound (the ‘go sound’) — they pecked on the sensor again, they received a reward. Pecking on the sensor after hearing the so-called no-go sound gave them no reward, and even ‘punished’ the birds by leaving them in the dark for a short while.

Dr Pralle Kriengwatana: ‘Our meta-analysis shows that female zebra finches learn to discriminate sounds faster, which is surprising considering that females don’t sing. On the basis that male songbirds usually sing more than female songbirds, scientists have long assumed that the males must also be better at recognising and learning song (and perhaps also other sounds). It now seems that sex differences in producing complex sounds do not necessarily correlate exactly with the ability to perceive and discriminate these complex sounds.’

The scientists are still in the dark about the reasons why females learn better than males, although the female hormone oestrogen may play a role. According to Kriengwatana, further research is needed to determine the precise cause of the sex differences.

The researchers also discovered that the zebra finches try out different theories in their efforts to understand the test. In the first instance some birds stop pecking as soon as they hear new sounds, and then start pecking after each sound (both ‘go’ and ‘no-go’). Once they realise that pecking after the ‘no-go’ sound does not bring them any reward, they peck much less after this sound. The other group of birds also initially stop pecking, and then slowly but surely start pecking on the LED sensor again after both sounds. As soon as they understand that the ‘go’ sound gives them food, they peck more after hearing this sound.

Surprisingly enough, family size and body mass also seem to play a role. The finches from larger nests learned to distinguish sounds faster than birds with fewer siblings. The same applied for finches that weighed more at the age when they learned to eat by themselves and stop relying on parents for food. One explanation could be that more contact with other birds and better health may promote the faster recognition of sounds.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160512130332.htm  Original web page at Science Daily

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* Why vultures matter, and what we lose if they’re gone

Researchers highlight ecosystem, human impacts of vulture declines. Cartoon characters in parched deserts often wish them to disappear, since circling vultures are a stereotypical harbinger of death. But, joking aside, vultures in some parts of the world are in danger of disappearing. And according to a new report from University of Utah biologists, such a loss would have serious consequences for ecosystems and human populations alike.

The primary threat to vultures, according to the report published today in Biological Conservation, is the presence of toxins in the carrion they consume. On many continents, vultures are the unfortunate victims of poisoned carcasses — especially impactful because dozens — or even hundreds — of vultures can feast on a single carcass. Populations of most vulture species around the world are now either declining or on the brink of extinction.

Losses of vultures can allow other scavengers to flourish, according to biologists Evan Buechley and Çağan Şekercioğlu. Proliferation of such scavengers could bring bacteria and viruses from carcasses into human cities.

In 2004, Şekercioğlu published a study examining the respective extinction risks of all bird species throughout the world. He noted then that vultures represented the single most threatened group of birds. Now, more than a decade later, Buechley and Şekercioğlu have examined factors affecting the extinction risk of more than 100 bird species, including 22 species of vultures, which eat carrion exclusively, and other scavenging birds that have broader diets.

Their results suggest several inherent ecological traits that likely contribute to vultures’ extinction risk, including their large body masses, slow reproductive rates and highly specialized diets. The greatest external threat to vultures, however, is poisoning.

Poisoning is the greatest extinction risk facing vultures, and impacts 88 percent of threatened vulture species. The poisons come in many forms.

In North America, the California condor, a vulture, experienced sharp declines until only 22 individuals remained by 1982. The leading cause of decline? Toxic lead bullet fragments in the gut piles left behind by hunters after animals had been field-dressed. Intensive conservation efforts helped the species to rebound. The condors now number well over 400, and range over large areas of California, Arizona, Utah and Baja California, Mexico.

In the mid-1990s India experienced a precipitous vulture decline, with more than 95 percent of vultures disappearing by the early 2000s. “That was a massive collapse that led a lot of people to really focus more attention on vultures,” Buechley says. The cause was eventually traced to diclofenac, a veterinary anti-inflammatory drug that relieved pain in cattle, but proved highly toxic to vultures. Hundreds of vultures would flock to each cattle carcass. And if the cow had recently been treated with diclofenac, hundreds of vultures would die. Because of this highly gregarious feeding behavior, less than one percent of cattle carcasses contaminated with diclofenac could account for the steep vulture decline. Fortunately, international cooperation led to a total ban on veterinary diclofenac use. Buechley says the numbers of vultures have stabilized, and are now showing signs of slowly increasing.

Now, the center of the vulture crisis is in sub-Saharan Africa. “In Africa, it’s a lot more challenging,” Buechley says. “It’s a darker story.” Potent newly affordable poisons are used to control predatory pests, such as lions or jackals. The poisons are so toxic that they can cascade through ecosystems: birds, mammals and insects are often found littering the area around these poisoned carcasses. But, as the predominant scavenger, vultures take the brunt of the poisoning and face the largest number of casualties. For example, an elephant carcass poisoned in Namibia in 2007 killed as many as 600 vultures. In other cases, vultures are the victims of poachers who poison carcasses so that vultures do not give away the location of illegally taken animals. “Vultures are taking the hit, indirectly, for a lot of this human-wildlife conflict, as well as the illegal trade in animal parts,” Buechley says. This crisis, unfortunately, is ongoing.

In vultures’ absence, other scavenger populations increase to take advantage of all of the uneaten carrion. By some estimates, in Central America, South America and Africa, vultures eat more meat than all predators combined. Without vultures, animals that eat carrion as a part of their diet (called facultative scavengers, as opposed to vultures, which eat only carrion) proliferate to take advantage of the available nutrients in a dead carcass. “There are a ton of nutrients in carrion that are going to be taken advantage of by something,” Buechley says.

Crows, rats, dogs — any of these species can suddenly become abundant and dominant, to the point of crowding out the remaining vultures. Hundreds of vultures on a carcass can easily frighten away packs of dogs, Şekercioğlu says. But when only a few vultures are left, the dogs can rule.

Such changes in populations of certain animal groups can upset the balance of food webs. “All these facultative scavengers are also predators, and so they also go out and eat other organisms too,” Buechley says. “You have this cascading effect.”

The impact of vultures’ declines are not limited to the realm of ecology, however. Vultures are highly efficient consumers of carrion, sometimes locating and consuming carcasses within an hour, before other forms of decay can set in. And vultures’ stomachs are highly acidic, killing nearly all bacteria or viruses that may be present in carrion. Combined with the fact that vultures rarely come in contact with humans, vultures serve as a barrier to prevent diseases from proliferating in dead animals and spreading to humans. Other facultative scavengers are not so adapted, and could pass along those diseases into human populations, as many are already fixtures in cities.

For example, following the decline of vultures, India experienced a strong uptick in feral dogs — by an estimated seven million. The increase in dogs, potentially feeding on disease-ridden carcasses, is thought to have at least partially caused the rabies outbreak that was estimated to have killed 48,000 people from 1992-2006 in India — deaths that may have been avoided if not for the disappearance of vultures.

Members of the Parsi sect of Zoroastrianism experienced a different impact. For thousands of years, the Parsi people have placed their dead on exposed mountaintops or tall towers for vultures to consume. The practice is called “sky burial.”

But with few vultures and unable to properly handle their dead, the Parsis experienced a crisis within the faith. Some constructed captive vulture aviaries. Others talked about desiccating bodies using focused solar mirrors. The Parsis’ plight exemplifies the vultures’ role in south Asian society — and the various impacts if the vultures aren’t there.

Although the vulture crisis in Africa is ongoing, Buechley and Şekercioğlu can predict what the outcome will be, based on previous experiences in India. Crows, gulls, rats and dogs will boom. And the rabies outbreak in India may just be a prologue, because several sub-Saharan Africa countries already have the highest per-capita rabies infection rates in the world. Rabies is only one of the many potential diseases that vultures had helped regulate.

Buechley notes that the poisoning that is killing vultures is also affecting many other organisms throughout ecosystems. But vultures are the most sensitive canaries in ecological coal mines. The story of the California condor shows that recovery is possible, but at a high cost that countries in the developing world may not be able to pay.

“It’s good news and bad news,” Şekercioğlu says. “It shows that we can bring back these scavengers. But the bad news is that once we get to these numbers, it costs tens of millions of dollars and decades to bring them back. You don’t want to go there. And once you go there, we can afford to save only a few species.”

So, Buechley argues, “the better solution is to invest in vulture conservation here and now, in order to stem incalculable damage from trophic cascades and increased human disease burden in the developing world.”

The study was funded by a National Science Foundation Graduate Research Fellowship and by the University of Utah’s Global Change and Sustainability Center.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160505145035.htm  Original web page at Science Daily

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How Arctic spring kills birds in Africa

Red knot birds are becoming smaller as temperatures warm in their Arctic breeding grounds. But the migrating birds don’t pay the price for this climate-caused shrinkage until they arrive at the more stable climate of their tropical winter homes. Having analyzed the data collected for more than three decades, scientists managed to show that the effects of climate changes in the Arctic may come out on a completely different continent, a few thousand kilometers away from the Arctic ice.

One of the authors, Eldar Rahimberdiev, researcher at the Biological faculty of MSU, says that the work is unique, as earlier scholars did not consider these problems so complex.

This article considers a small bird of the suborder waders — red knot (Calidris canutus). This bright red in summer and almost white in winter bird is one of a record-breakers for distance flight, being able to cover about 5000 kilometers non-stop. Every year in the autumn it flies to winter at the coast of Mauritania (or, depending on the subspecies, Australia or South America), and in the spring returns to breed on Taimyr peninsula — the northernmost mainland of Eurasia (or, again, depending on the subspecies, Greenland, Alaska and the Canadian Arctic archipelago). And then the bird has another record, choosing the most northern and cold nesting latitudes. The arrival of the red knots to these severe lands was “calculated” by evolution so that the birth of the chicks happens just at the peak of abundance of insects, their main food.

But that was before the global warming has seriously changed the lives of the birds within a few decades. These changes are described in the new article. At the disposal of the researchers was a data archive for 33 years, which included complete measurement by Polish scientists on the morphology changes in 1990 juvenile birds who committed intermediate stops in Poland within this period, and satellite images of the Taimyr Peninsula and the results of the Dutch zoologists’ observations on the birds at the coasts of Mauritania.

During these 30 years the arrival of spring on the Taimyr Peninsula, and the peak of the insect population moved for almost two weeks earlier in time. If the snow on the peninsula disappeared by the middle of July in the past, it is gone now at the end of June. Arrival dates of birds stayed stable, but phenologically birds begin to nest later than 30 years ago, and miss the peak of insect abundance essential for juvenile growth. The lack of food has caused a decrease in the size of the young birds, which is impossible be compensated later in life. However, at first glance, the problems for birds did not increase: with the arrival of cold weather, young red knots still go to their long journey and still successfully get to Africa, preparing to spend the whole winter there, and fly back only in spring. But the real difficulties come further. During the winter in the Banc d’Arguin National Park in Mauritania, red knots eat bivalve mollusks hiding in the sediment, and they need quite a long bill for reaching this food. Birds with long beaks often diversify their diet with Loripes lucinalis, burrowing deep enough into the sand. Even though that shellfish produces a toxin in their body, in a birds’ diet its proportion may be up to 40%. Red knots with a shorter bill reach another food source — Dosinia isocardia, and those not lucky with the length of the beak are to be fed with plant food — small rhizomes of Zostera (Zostera noltii). Survival rate of the birds that are not able to get to mollusks Loripes was significantly lower than those which were not restricted in their diet.

Dietary restrictions imposed on too short-beak birds particularly impact the young birds, most of them are unable to survive their first winter. Thus, the consequences of the problem that occurred in the Arctic act in a few months, and moreover — on another continent. If the knot still manages to fly back on the Taimyr Peninsula, a short break even helps — to hunt insects is much easier than with a long one. But, as practice shows, the birds hardly survive in Africa.

According to Eldar Rahimberdiev, researcher of the biological faculty of the Lomonosov MSU, the threat of extinction is more than real for red knots. Now populations of all northern waders greatly decreases, some subspecies are already on the edge of extinction. If the bird’s bill is reduced to such an extent that they will not manage at all to get shellfish, the species will simply disappear. Moreover, many birds of the population are already close to the critical point, when any random fluctuations of numbers can destroy the population.

The work of scientists is unique, as the authors have shown that the transfer of the appeared problem is possible only in time but also in space. Earlier the articles of such level did not appear in Science magazines, and scientists, according to Eldar Rahimberdiev, rarely paid attention to the whole annual cycle.

‘When I was a student and worked with the same species, we were always arguing with foreign colleagues, who said that the birds die because the problems occur during migration. We thought that the problem was at the breeding grounds. And those who worked on the wintering grounds in Africa, argued that there is no problem in Africa. Now it becomes clear that all these parts are interconnected and a sharp change in any part leads to unexpected consequences,’ the scientist says.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160512145457.htm Original web page at Science Daily

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Highway noise deters communication between birds

New research from University of Florida Institute of Food and Agricultural Sciences researchers shows birds may be avoiding habitats near noisy highways because they can’t hear fellow birds’ alarms that warn them of attacking hawks or owls. Some highways cut through or run along natural areas, and researchers know that wild birds often make their homes away from those highways, but they don’t know why.

UF/IFAS researchers tested whether highway noise could be interfering with bird communication. Results of their study suggest too much noise around these highways keeps birds from hearing warnings from fellow birds about predators in the area, and that puts them at a higher risk of being eaten. It is also possible that the birds are hearing the alarms, but are too distracted by the noise to respond to them.

The researchers caution that they did not establish a causal link between highway noise and bird population reductions, although noise-disrupting alarm calls is a compelling possibility.

“Conservation of bird species should include decreasing noise in sensitive wildlife areas,” said Aaron Grade, who led the study as part of his master’s thesis in the UF/IFAS wildlife ecology and conservation department.

Grade and his graduate adviser, UF/IFAS wildlife ecology and conservation professor Katie Sieving, tested the abilities of northern cardinals to hear the predator alarm of tufted titmice by playing alarm calls to cardinals through speakers in both noisy and quiet locations in Florida state parks. They found that noise from vehicles along the busy highways often drowns out the alarms emitted by birds. Researchers went to Florida state forests near Interstate 75 and U.S. 441 in Alachua, Marion and Columbia counties to test whether highway noise could interfere with bird communication.

Northern cardinals and tufted titmice are two abundant bird species in the woods of eastern North America. Many bird and mammal species rely on information from tufted titmice calls to detect and respond to dangerous predators. This causes important information networks to form around tufted titmouse communication. Normally, northern cardinals listen to tufted titmouse predator alarm calls and will typically respond by fleeing or freezing until the danger passes.

But when tested near noisy roads, cardinals failed to respond to titmouse alarm calls, suggesting that the noise may prevent cardinals from escaping when there are dangerous predators around, Sieving said.

“Our work suggests that disruption of animal communication networks could hinder natural behaviors of wildlife and help explain patterns of reduced biodiversity near roadways,” said Grade, now a doctoral student at the University of Massachusetts.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/05/160511093144.htm Original web page at Science Daily

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Tropical birds develop ‘superfast’ wing muscles for mating, not flying

Studies in a group of tropical birds have revealed one of the fastest limb muscles on record for any animal with a backbone. The muscle, which can move the wing at more than twice the speeds required for flying, has evolved in association with extravagant courtship displays that involve rapid limb movements, according to a paper to be published in the journal eLife.

The ‘superfast’ wing movements of male red-capped and golden-crowned manakins are undetectable to the human eye, and are about six to eight times faster than the 8-hertz (Hz) speed at which a sprinter, such as Olympian athlete Usain Bolt, moves their legs through the air in a 100-metre run.

“The discovery of the superfast wing muscle in these birds paves the way for further studies into what has to change, or what can change, in a muscle to make it drive faster movements,” says first author Matthew Fuxjager, from Wake Forest University.

“This could be important for developing therapies for motor disorders, particularly those characterized by decreases in muscle performance that result from diseases such as cancer and HIV.”

Many different species perform rapid limb movements as part of their courtship displays, from certain birds running across lake surfaces, to the unusual boxing displays of hares in March.

However, because muscle performance is limited by trade-offs between speed and force, it is unclear how animals develop the ability to generate both the swift movements involved in showy physical displays and the force needed to drive these movements.

To address this question, Fuxjager and his team compared the twitch speeds of forelimb muscles from wild-caught golden-collared and red-capped manakins to those of three other related species: the blue-crowned manakin, the dusky antbird, and the house wren.

“Of the species studied, the golden-collared and red-capped manakins produce exceptionally rapid wing movements as part of their acrobatic courtship displays,” Fuxjager explains.

“For example, the golden-collared manakins perform ‘roll-snaps’, whereby they hit their wings together above the back at around 60 Hz to produce a loud mechanical sound. Likewise, red-capped manakins produce a similar wing sonation called a ‘clap’, in which the wings are extended slightly above the body and immediately retracted back to the sides in quick succession, at around 45 Hz.”

To explain these birds’ abilities to move their limbs rapidly during courtship performances, the researchers investigated the differences in muscle contraction speeds by comparing the half-relaxation frequency among the five different species. This represents the frequency at which each wing muscle is stimulated to contract, while still being able to relax to half their length following stimulation, thereby showing an accurate measure of how quickly they can contract.

For two of the three wing muscles, the half-relaxation frequencies averaged around 50 Hz and were indistinguishable among species. By contrast, the frequency measures in the main muscle that retracts the humerus were significantly higher in both the golden-collared and red-capped manakins. Estimates of their half-relaxation frequencies in this muscle were exceptionally high, and the frequencies between the two birds were indistinguishable.

These results show that only the golden-collared and red-capped manakins have evolved superfast contractile movements in their main humeral retractor muscle. The other two muscles that generate the majority of aerodynamic force for flight are no different from those of other birds, suggesting that they have been preserved to produce the strength needed for flying.

The team also found that the humeral retractor muscle in golden-collared and red-capped manakins is more than capable of driving the natural wing oscillations that make up their impressive displays.

Taken together, the results suggest that muscle-specific adaptations in contractile speed allow certain birds to avoid the trade-off between muscular speed and force, thereby using their forelimbs for both rapid gestural displays and powered locomotion.

“Further studies could now explore how this one muscle can create such superfast wing movements and whether male hormones, such as testosterone, play a role in regulating the muscle’s speed,” Fuxjager adds.

“If we discover whether steroids regulate the muscle’s ability to contract at superfast speed, we would be uncovering how hormones can ‘turn on’ or ‘turn off’ its extraordinary ability. This would open the door to understanding how rapid limb movements are regulated in accordance with the animals’ reproductive environment.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/04/160412104805.htm  Original web page at Science Daily

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Evolution of Darwin’s finches tracked at genetic level

Researchers are pinpointing the genes that lie behind the varied beaks of Darwin’s finches – the iconic birds whose facial variations have become a classic example of Charles Darwin’s theory of natural selection.

Last year, researchers identified a gene that helps to determine the shape of the birds’ beaks. Today in Science, they report a different gene that controls beak size. Shifts in this gene underlay an evolutionary change that researchers watched in 2004–05, during a drought that ravaged the Galapagos Islands, where the finches live. The beak sizes of one population of finches shrank, so as to avoid competing for food sources with a different kind of finch – and their genetics changed accordingly.

“A big question was, ‘Is it possible to identify genes underlying such evolution in action, even in a natural population?’,” says Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s authors. “We were able to nail down genes that have directly played a role in this evolutionary change.”

The story begins about two million years ago, when the common ancestor of all Darwin’s finches arrived on the Galapagos Islands. By the time of Charles Darwin’s visit in 1835, the birds had diversified into more than a dozen species, each adapted to different ecological niches. Some had massive beaks for cracking seeds, some had delicate beaks for snatching insects, and some even had sharp beaks for feeding on blood.

To examine the genetic basis for this variation, the researchers compared the genomes of 60 birds representing six species of Darwin’s finches, along with 120 specimens from other species to help them tease out phylogenetic relationships. As expected, closely related species had the most similar genomes.

But in those six finch species one region of the genome correlated more with bird size than with relatedness. Small species had one variation of this genomic region, large species had another and medium-sized species had a mixture of the two, suggesting that at least one of the genes in this region affected size. The most likely candidate was HMGA2, which is known to affect size and face structure in other animals. Further analysis showed that in Darwin’s finches, the HMGA2 region is especially important in controlling the size of the beak.

The researchers then looked at the role of HMGA2 in a dramatic evolutionary event. After drought struck the Galapagos in 2003, many of the medium ground finches (Geospiza fortis) with larger-than-average beaks starved to death. They couldn’t compete with a bigger species (Geospiza magnirostris) that had recently colonized the island and was better at eating large seeds. After the drought, the medium ground finches that managed to survive had smaller beaks than those that had perished, probably because they were better suited to eating the small seeds that their competitors avoided.

By analysing DNA from medium ground finches that lived around the time of the drought, the researchers found that the large-beak HMGA2 variant was more common in birds that starved to death, while the small-beak variant was more common in birds that survived. This genetic shift is likely responsible for some of the reduction in beak size, the researchers say.

The discovery opens up new questions for biologists to explore, such as when gene variants arise and how they contribute to splits between species, says Dolph Schluter, an evolutionary biologist at the University of British Columbia in Vancouver, Canada.

“On the one hand it doesn’t change anything, in that we already knew there was an evolutionary response to competition during that drought,” says Schluter. “But on the other hand, it changes everything, because we can point to a physical, material basis for that change.”

Nature doi:10.1038/nature.2016.19795

http://www.nature.com/news/index.html  Nature

http://www.nature.com/news/evolution-of-darwin-s-finches-tracked-at-genetic-level-1.19795 Original web page at Nature

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Despite their small brains, ravens and crows may be just as clever as chimps, research suggests

A study led by researchers at Lund University in Sweden suggests that ravens can be as clever as chimpanzees, despite having much smaller brains, indicating that rather than the size of the brain, the neuronal density and the structure of the birds’ brains play an important role in terms of their intelligence.

“Absolute brain size is not the whole story. We found that corvid birds performed as well as great apes, despite having much smaller brains,” says Can Kabadayi, doctoral student in Cognitive Science.

Intelligence is difficult to test, but one aspect of being clever is inhibitory control, and the ability to override animal impulses and choose a more rational behaviour. Researchers at Duke University, USA, conducted a large-scale study in 2014, where they compared the inhibitory control of 36 different animal species, mainly primates and apes. The team used the established cylinder test, where food is placed in a transparent tube with openings on both sides. The challenge for the animal is to retrieve the food using the side openings, instead of trying to reach for it directly. To succeed, the animal has to show constraint and choose a more efficient strategy for obtaining the food.

The large-scale study concluded that great apes performed the best, and that absolute brain size appeared to be key when it comes to intelligence. However, they didn’t conduct the cylinder test on corvid birds.

Can Kabadayi, together with researchers from the University of Oxford, UK and the Max Planck Institute for Ornithology in Germany, therefore had ravens, jackdaws and New Caledonian crows perform the same cylinder test to better understand their inhibitory control.

The team first trained the birds to obtain a treat in an opaque tube with a hole at each end. Then they repeated the test with a transparent tube. The animal impulse would naturally be to go straight for the tube as they saw the food. However, all of the ravens chose to enter the tube from the ends in every try. The performance of the jackdaws and the crows came very close to 100%, comparable to a performance by bonobos and gorillas.

“This shows that bird brains are quite efficient, despite having a smaller absolute brain size. As indicated by the study, there might be other factors apart from absolute brain size that are important for intelligence, such as neuronal density,” says Can Kabadayi, and continues:

“There is still so much we need to understand and learn about the relationship between intelligence and brain size, as well as the structure of a bird’s brain, but this study clearly shows that bird brains are not simply birdbrains after all!”

https://www.sciencedaily.com/ Science Daily

https://www.sciencedaily.com/releases/2016/04/160426101527.htm Original web page at Science Daily

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With ravens, out of sight is not out of mind

The question of what sets humans apart from other animals is one of the oldest philosophical puzzles. A popular answer is that only humans can understand that others also have minds like their own.

But new research suggests that ravens — birds singled out by many cultures as a symbol of intelligence and wisdom — share at least some of the human ability to think abstractly about other minds, adapting their behavior by attributing their own perceptions to others.

The study, “Ravens Attribute Visual Access to Unseen Competitors,” was published Feb. 2 in Nature Communications. It found that ravens guarded caches of food against discovery in response to the sounds of other ravens if a nearby peephole was open, even if they did not see another bird. They did not show the same concern when the peephole was closed, despite the auditory cues.

The findings shed new light on science’s understanding of Theory of Mind, the ability to attribute mental states — including vision — to others, said Cameron Buckner, assistant professor of philosophy at the University of Houston. Buckner is an author of the paper, along with Thomas Bugnyar and Stephan A. Reber, cognitive biologists at the University of Vienna.

Most Theory of Mind research involving animals has been done with chimpanzees and other species closely tied to humans. But while those studies have suggested that animals are able to understand what others see — giving them an advantage in competing for food, for example — they rely on the test subjects’ ability to see another’s head or eyes, providing so-called “gaze cues.” Skeptics argue that animals in these experiments might be responding only to these surface cues, without any real understanding of what others see.

“Thus,” the authors write describing the previous state of the research, “it still remains an open question whether any nonhuman animal can attribute the concept ‘seeing’ without relying on behavioral cues.”

Buckner, who focuses on animal cognition, said the researchers avoided that concern in this experiment by using only open peepholes and sounds to indicate the presence of a possible competitor, with the ravens never physically able to see another raven in the context of the experiment.

Ravens are a good subject for study, he said, because despite their obvious evolutionary divergence from humans, their social lives go through several distinct phases, similar to people. In particular, they often defend territories in stable breeding pairs as adults but live in more fluid situations as adolescents.

“There is a time when who is in the pack, who’s a friend, who’s an enemy can change very rapidly,” he said. “There are not many other species that demonstrate as much social flexibility. Ravens cooperate well. They can compete well. They maintain long-term, monogamous relationships. This all makes them a good place to look for social cognition, because similar social pressures might have driven the evolution of similarly advanced cognitive capacities in very different species.”

The ability to cache food is important to ravens, and previous research had shown they behave differently when they perceive a competitor watching. For example, when ravens are being watched, they hide food more quickly and are less likely to return to a previously made cache, both of which might reveal the location of a cache to a possible pilferer. If they do not think they are being watched, they spend more time on the task.

This study involved two rooms, connected both by windows, which could be opened or covered, and by peepholes, which could be open or closed. The ravens were trained to look through the peepholes to observe a human experimenter making caches in the adjacent room. During the final phase of the test, both windows were covered but a peephole was open. A hidden speaker played sounds of a raven competitor, but no other bird was present. The subjects still cached as though they were being watched.

“We show that ravens … can generalize from their own experience using the peephole as a pilferer and predict that audible competitors could potentially see their caches (through the peephole),” the authors write. “Consequently, we argue that they represent ‘seeing’ in a way that cannot be reduced to the tracking of gaze cues.”

The findings offer needed information in several arenas, Buckner said, including evidence that ravens could serve as animal models in research involving social cognition.

It also offers new evidence about the capacities involved in Theory of Mind and abstract thinking, Buckner said. “It could change our perception of human uniqueness, that we share some of that ability not just with chimpanzees and closely related species but also with a very different species.”

Buckner said the next step will be to see which other animals are capable of the kind of abstraction assessed in the peephole test, “especially humans, since we don’t know when this ability emerges in childhood.

“Finding that Theory of Mind is present in birds would require us to give up a popular story as to what makes humans special,” he said. “But completing this evolutionary and developmental picture will bring us much closer to figuring out what’s really unique about the human mind.”

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/02/160202143129.htm  Original web page at Science

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* Small birds’ vision: Not so sharp but superfast

One may expect a creature that darts around its habitat to be capable of perceiving rapid changes as well. Yet birds are famed more for their good visual acuity. Joint research by Uppsala University, Stockholm University and the Swedish University of Agricultural Sciences (SLU) now shows that, in small passerines (perching birds) in the wild, vision is considerably faster than in any other vertebrates — and more than twice as fast as ours.

The new research findings are published in the scientific journal PLOS ONE.

In behavioural experiments, the scientists have studied the ability to resolve visual detail in time in three small wild passerine species: blue tit, collared flycatcher and pied flycatcher. This ability is the temporal resolution of eyesight, i.e. the number of changes per second an animal is capable of perceiving. It may be compared to spatial resolution (visual acuity), a measure of the number of details per degree in the field of vision.

The researchers trained wild-caught birds to receive a food reward by distinguishing between a pair of lamps, one flickering and one shining a constant light. Temporal resolution was then determined by increasing the flicker rate to a threshold at which the birds could no longer tell the lamps apart. This threshold, known as the CFF (critical flicker fusion rate), averaged between 129 and 137 hertz (Hz). In the pied flycatchers it reached as high as 146 Hz, some 50 Hz above the highest rate encountered for any other vertebrate. For humans, the CFF is usually approximately 60 Hz. For passerines, the world might to be said to be in slow motion compared with how it looks to us.

It has been argued before, but never investigated, that small and agile wild birds should have extremely fast vision. Nevertheless, the blue tits and flycatchers proved to have higher CFF rates than were predicted from their size and metabolic rates. This indicates an evolutionary history of natural selection for fast vision in these species. The explanation might lie in small airborne birds’ need to detect and track objects whose image moves very swiftly across the retina — for blue tits, for example, to be able to see and avoid all branches when they take cover from predators by flying straight into bushes. Moreover, the three avian species investigated all, to a varying degree, subsist on the insects they catch. Flycatchers, as their name suggests, catch airborne insects. For this ability, aiming straight at the insect is not enough. Forward planning is required: the bird needs high temporal resolution to track the insect’s movement and predict its location the next instant.

The new results give some cause for concern about captive birds’ welfare. Small passerines are commonly kept in cages, and may be capable of seeing roughly as fast as their wild relatives. With the phase-out of incandescent light bulbs for reasons of energy efficiency, tame birds are increasingly often kept in rooms lit with low-energy light bulbs, fluorescent lamps or LED lighting. Many of these flicker at 100 Hz, which is thus invisible to humans but perhaps not to small birds in captivity. Studies have shown that flickering light can cause stress, behavioural disturbances and various forms of discomfort in humans and birds alike.

Of all the world’s animals, the eagle has the sharpest vision. It can discern 143 lines within one degree of the field of vision, while a human with excellent sight manages about 60. The magnitude of this difference is almost exactly the same as between a human’s top vision speed and a pied flycatcher’s: 60 and 146 Hz respectively. Thus, the flycatcher’s vision is faster than human vision to roughly the same extent as an eagle’s vision is sharper. So small passerines’ rapid vision is an evolutionary adaptation just as impressive as the sharp eyesight of birds of prey.

Anders Ödeen, the lecturer at Uppsala University’s Department of Ecology and Genetics who headed the study, puts the research findings in perspective.

‘Fast vision may, in fact, be a more typical feature of birds in general than visual acuity. Only birds of prey seem to have the ability to see in extremely sharp focus, while human visual acuity outshines that of all other bird species studied. On the other hand, there are lots of bird species similar to the blue tit, collared flycatcher and pied flycatcher, both ecologically and physiologically, so they probably also share the faculty of superfast vision.’

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/03/160318144548.htm  Original web page at Science

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Botulism in waterbirds: Mortality rates and new insights into how it spreads

Outbreaks of botulism killed large percentages of waterbirds inhabiting a wetland in Spain. During one season, more than 80 percent of gadwalls and black-winged stilts died. The botulinum toxin’s spread may have been abetted by an invasive species of water snail which frequently carries the toxin-producing bacterium, Clostridium botulinum, and which is well adapted to wetlands polluted by sewage. Global warming will likely increase outbreaks, said corresponding author Rafael Mateo, PhD. The research was published March 25th in Applied and Environmental Microbiology, a journal of the American Society for Microbiology.

Botulism is a major killer of waterbirds, including some endangered species. In earlier studies, some also published in Applied and Environmental Microbiology, these investigators had found that eutrophication of some of these wetlands, due to effluent from waste water treatment plants, was encouraging growth of C. botulinum and other bacterial pathogens of birds.

In the current study, the investigators surveyed mortality among the resident waterbirds, and investigated how the bacterium is spread. During two outbreaks, the investigators collected 43 dead white-headed ducks, representing seven percent and 17 percent of their maximum population on Navaseca lake during 2011 and 2012, respectively, said Mateo, who is Head of the Group of Wildlife Toxicology, at the Spanish Institute of Game and Wildlife Research, Cuidad Real, Spain. White-headed ducks are highly endangered, with only about ten thousand surviving individuals worldwide.

Additionally, the team found death rates of greater than 80 percent among gadwalls and black-winged stilts in 2011. Mortality estimates for white-headed ducks are probably low, said Mateo, explaining that scavengers frequently devour dead birds, and that it is difficult to find ailing or expired avians in the dense vegetation along the lake shore.

The team also investigated how the disease spreads. The main source of spread, previously known, is the “carcass-maggot cycle,” said Mateo. “Birds feed on maggots growing in a carcass containing C. botulinum and its neurotoxin,” and then die, with the cycle beginning anew as the dead birds become food for more maggots. “The spread of the outbreak is exponential,” said Mateo.

Additionally, the investigators found that 30 percent of an invasive species of freshwater snail, collected during outbreaks, carried C. botulinum. These snails, Physa acuta, are an invasive species that is well adapted to wetlands polluted by sewage. They are likely sources of food for a number of different waterbird species, including mallards, gulls, and coots, said Mateo.

Differences in diets result in different levels of vulnerability among bird species. Flamingos and grebes appeared untouched by outbreaks, likely because they appear to feed mainly on prey species that do not carry C. botulinum, such as certain crustaceans, and/or possibly because they are more resistant genetically than other species to this pathogen.

Mateo warned that outbreaks would likely occur more frequently due to global warming. In earlier research, also published in Applied and Environmental Microbiology, his group showed that higher summer temperatures are associated with higher mortality rates among waterbirds during outbreaks. “We have observed that outbreaks occur when the mean temperature in July exceeds 26˚C [79˚F.],” he said. Additionally, when water is scarce due to drought, wetlands eutrophy more frequently, which favors anaerobic bacteria such as C. botulinum. Finally, birds tend to concentrate in the few wetlands that are maintained with treated sewage, which boosts mortality from botulism and other diseases, he said.

These wetlands, which are located in La Mancha, which was made famous by the novel, Don Quixote, and which are rich in biodiversity, are a UNESCO “biosphere reserve.” Their unique habitat is important for many bird species, including migratory birds that breed there, such as the afore-mentioned white-headed duck. But outbreaks of botulism are common. “We wanted to characterize the ecology of the avian botulism in these wetlands to know to what degree human action–notably poor treatment of sewage–was determining the outbreaks’ occurrence,” said Mateo.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/03/160325151729.htm  Original web page at Science Daily

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* Songbirds pinpoint effects of Huntington’s disease

Although Huntington’s disease is caused by mutations in a single gene, understanding how it ravages the brain and body has been anything but simple.

A new study by Duke University scientists parses the role of the Huntington’s disease gene in an area of the brain responsible for complex, sequential movements like those used to talk to a friend, play the violin, or swing a golf club.

Described March 7 in the Proceedings of the National Academy of Sciences, the findings not only give a clearer view of how the genetic mutation that causes Huntington’s disease alters brain and behavior, it may also offer a new therapeutic target for treatment.

“These new results make a direct link between the genetic mutation, the insults that mutation causes to brain structure and function, and the behavioral pathology,” said Richard Mooney, the George Barth Geller Professor of Neurobiology in the Duke School of Medicine.

Last year, researchers at the Rockefeller University in New York described a genetically altered songbird that shows an array of symptoms reminiscent of Huntington’s disease, such as tremor, body stiffness and difficulties vocalizing.

The songbird is ideal for studying Huntington’s disease, Mooney said, because of the way evolution has enhanced the regions of its brain that are important in learning and singing songs. A song is produced by a string of precise movements of the vocal and respiratory muscles. Because each bird normally sings the same way every time, researchers can easily measure and detect subtle changes to the birds’ movements caused by a faulty gene.

The Rockefeller group expressed the mutated gene throughout the entire brain and body of the songbird, affecting many behaviors. That made it difficult to draw direct connections between the genetic mutation, specific brain changes, and problems making complex movements.

In the new study, using the same species of songbird, Mooney’s group introduced the mutated gene in just one region of the brain called the basal ganglia, which is especially vulnerable to the disease.

Buried deep in the brain, the basal ganglia comprise a network of nerve cells that help start and stop movements and organize sequences of actions. The researchers introduced the Huntington’s disease gene only in a small region of the basal ganglia called ‘area X’, which is important for learning and singing songs in birds.

Within two months of receiving the virus carrying the gene mutation, the songbirds sang abnormal songs, and more songs in general, compared to healthy birds. The syllables of the songs were normal, but as with people with Huntington’s disease, the birds had trouble producing syllables in the right order and halting their songs once they had started them.

The mutation affected a specific type of neuron (medium spiny neuron) in area X. Another type of neurons (pallidal), which are the main output neurons of the basal ganglia, survived. But the timing of the pallidal neurons’ activity became unreliable when the study’s lead author Masashi Tanaka, a postdoctoral associate in Mooney’s lab, measured them in singing birds.

“That suggests that there’s something lost in the complexity of the signals that these output neurons normally transmit,” said Mooney, who is a member of the Duke Institute for Brain Sciences. “If that’s the case, then you could imagine that if you reinstituted more complex patterns of activity, that may be sufficient to restore normal behavior.”

The researchers also found that shutting off the main output of area X was sufficient to restore normal songs in the birds. It may be that no output from the basal ganglia is better than the wrong kind, Mooney said.

Mooney’s team has anecdotally observed that with time, a small subset of the songbirds stabilize their songs. They don’t recover completely, but their songs show fewer abnormalities. Mooney hopes to understand why. It could be because adult songbirds can generate new medium spiny neurons, unlike humans.

“If new neurons drive recovery, it may be that the songbird will provide a model for understanding how neural replacement in humans can be used to drive behavioral recovery in a range of neurodegenerative diseases,” Mooney said.

https://www.sciencedaily.com/  Science Daily

https://www.sciencedaily.com/releases/2016/03/160307152720.htm  Original web page at Science Daily