Fossils of first feathered dinosaurs from North America discovered: Clues on early wing uses

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Fossils of First Feathered Dinosaurs from North America Discovered: Clues On Early Wing Uses

ScienceDaily (Oct. 25, 2012)The ostrich-like dinosaurs in the original Jurassic Park movie were portrayed as a herd of scaly, fleet-footed animals being chased by a ferocious Tyrannosaurus rex. New research published in the journal Science reveals this depiction of these bird-mimic dinosaurs is not entirely accurate -- the ornithomimids, as they are scientifically known, should have had feathers and wings.

This is an artistic reconstruction of feathered ornithomimid dinosaurs found in Alberta. (Credit: Julius Csotonyi)
The new study, led by paleontologists Darla Zelenitsky from the University of Calgary and François Therrien from the Royal Tyrrell Museum of Palaeontology, describes the first ornithomimid specimens preserved with feathers, recovered from 75 million-year-old rocks in the badlands of Alberta, Canada.
"This is a really exciting discovery as it represents the first feathered dinosaur specimens found in the Western Hemisphere," says Zelenitsky, assistant professor at the University of Calgary and lead author of the study. "Furthermore, despite the many ornithomimid skeletons known, these specimens are also the first to reveal that ornithomimids were covered in feathers, like several other groups of theropod dinosaurs."
The researchers found evidence of feathers preserved with a juvenile and two adults skeletons of Ornithomimus, a dinosaur that belongs to the group known as ornithomimids. This discovery suggests that all ornithomimid dinosaurs would have had feathers.
The specimens reveal an interesting pattern of change in feathery plumage during the life of Ornithomimus. "This dinosaur was covered in down-like feathers throughout life, but only older individuals developed larger feathers on the arms, forming wing-like structures," says Zelenitsky. "This pattern differs from that seen in birds, where the wings generally develop very young, soon after hatching."
This discovery of early wings in dinosaurs too big to fly indicates the initial use of these structures was not for flight.
"The fact that wing-like forelimbs developed in more mature individuals suggests they were used only later in life, perhaps associated with reproductive behaviors like display or egg brooding," says Therrien, curator at the Royal Tyrrell Museum and co-author of the study.
Until now feathered dinosaur skeletons had been recovered almost exclusively from fine-grained rocks in China and Germany. "It was previously thought that feathered dinosaurs could only fossilize in muddy sediment deposited in quiet waters, such as the bottom of lakes and lagoons," says Therrien. "But the discovery of these ornithomimids in sandstone shows that feathered dinosaurs can also be preserved in rocks deposited by ancient flowing rivers."
Because sandstone is the type of rock that most commonly preserves dinosaur skeletons, the Canadian discoveries reveal great new potential for the recovery of feathered dinosaurs worldwide.
The fossils will be on display this fall at the Royal Tyrrell Museum in Drumheller, Alberta.


Genomic Hitchhikers in Birds Shed Light On Evolution of Viruses

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ScienceDaily (Oct. 16, 2012)The genomes of birds are riddled with DNA sequences from viruses, according to a study to be published on Oct. 16 in mBio®, the online open-access journal of the American Society for Microbiology. Analysis of these viral sequences, known as endogenous retroviruses (ERVs), can provide insights into how both hosts and viruses have evolved over the eons.

"We examined the evolution of avian retroviruses on the basis of their fossil remnants in the three avian genomes that have been completely sequenced," write the authors from Johns Hopkins University and Uppsala University, Sweden. The authors go on to say their analyses of ERVs in chicken, turkey, and zebra finch genomes reveal that birds were a hotbed of viral evolution early in their history.
All genomes are cobbled together works-in-progress. Scientists have long known that the human genome, for example, is not all human: like most every other genome studied to date, a good chunk of the DNA we call "human" is actually made up of proviruses, sequences that retroviruses have deposited there to take advantage of the cell's ability to copy DNA and translate that DNA into working proteins. These proviruses can either be inherited in the DNA we get from our parents (endogenous retroviruses), or they can be picked up during our lifetime (exogenous retroviruses).
The study reveals that millions of years ago birds were host to many different kinds of ERVs, serving as a kind of melting pot: a meeting and mingling place where viruses recombined and shared genetic information.
Unlike early studies of ERVs in chickens, which studied selected segments of the genome and uncovered only alpha-retroviruses, this study used complete genome sequences and found a great diversity of viral sequences in bird genomes, representing the same major groups as those of mammals, but exhibiting more diversity. Most of the ERVs in birds were distinct from those found in other animals, probably indicating that the viruses did not move much between different kinds of hosts.
"We conclude that avian retroviral evolution differs from that of other vertebrates," write the researchers. "Avian retroviruses seem to have evolved rather independently from the rest of the retroviruses over the last 150 million years."
Stepher Goff of Columbia University, who was not involved in the research but edited the article for mBio®, says genome-level studies like this are a boon to virologists.
"This paper is filling a big gap in our understanding of these viruses," says Goff. "This is something that needed to be done, and advancing sequencing technology made it easy to do."

Crows Don't Digest Prions, May Transport Them to Other Locations

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ScienceDaily (Oct. 17, 2012)Crows fed on prion-infected brains from mice can transmit these infectious agents in their feces and may play a role in the geographic spread of diseases caused by prions, such as chronic wasting disease or scrapie.

The new research published Oct. 17 in the open access journal PLOS ONE by Kurt VerCauteren from the US Department of Agriculture (USDA) and other colleagues, shows that prions can pass through crows' digestive systems without being destroyed, and may be excreted intact after ingestion by the birds. According to the authors, their results demonstrate a potential role for the common crow in the spread of infectious diseases caused by prions.
Prions are infectious proteins that cause diseases in humans and other animals. Studies so far have suggested that insects, poultry and scavengers like crows may be passive carriers of infectious prions, but this is the first demonstration that prions can retain their ability to cause disease after passing through the avian digestive system.
The authors fed crows with brain samples from mice infected with prions, and found that the crows passed infectious prions up to 4 hours after eating the infected samples. When healthy mice were injected with the infected crow excretions, all the mice showed signs of prion disease. The authors state that their results support the possibility that crows that encounter infected carcasses or consume infected tissue may have the capacity to transport infectious prions to new locations.

Migratory Birds’ Ticks Can Spread Viral Haemorrhagic Fever

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ScienceDaily (Oct. 22, 2012)A type of haemorrhagic fever (Crimean-Congo) that is prevalent in Africa, Asia, and the Balkans has begun to spread to new areas in southern Europe. Now Swedish researchers have shown that migratory birds carrying ticks are the possible source of contagion.

The discovery is being published in the US Centers for Disease Control and Prevention journal Emerging Infectious Diseases.
Crimean-Congo Haemorrhagic fever is a serious disease that begins with influenza-like symptoms but can develop into a very serious condition with high mortality (30%). The disease occurs in Africa, Asia, and the Balkans but it has recently started to spread to new areas in southern Europe. It is caused by a virus that is spread by tick bites and common host animals are various small mammals and ungulates. Humans are infected by tick bites or close contact with contagious mammals.
Researchers have now studied the dissemination mechanisms of this potentially fatal disease. The study is multidisciplinary, with bird experts, tick experts, molecular biologists, virologists, and infectious disease physicians from Uppsala University and Uppsala University Hospital in collaboration with colleagues from the Swedish Institute for Communicable Disease Control, Kalmar and Linköping. Ornithologists and volunteers also helped gather birds.
During two spring seasons in 2009-2010, a total of 14 824 birds were captured at the two ornithological stations Capri (Italy) and Anticythera (Greece), on their way from Africa to Europe. A total of 747 ticks were gathered and analysed for the virus.
Some 30 different bird species were examined, and one species, the woodchat shrike, which winters in southern Africa and nests in Central Europe, proved to be a carrier of virus-infected ticks.
"This is the first time ticks infected with this virus have been found on migratory birds. This provides us with an entirely new explanation of how this disease, as well as other tick-borne diseases, has spread to new areas, where new mammal populations can be infected by the infected ticks," says Erik Salaneck, one of the authors of the study.
The Hyalomma tick, which spreads the disease, does not thrive in northern Europe, preferring warmer latitudes. But with a warmer climate, the boundary for both the tick species and the disease could move northward with the help of migratory birds.


Researchers Find Our Inner Reptile Hearts

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ScienceDaily (Sep. 14, 2012)The genetic building blocks behind the human heart's subtle control system have finally been identified.

The reptilian heart has a thin wall surrounding a spongy inner part. In many ways, this resembles the embryonic state in birds, humans and other mammals. The anatomy of their hearts is subsequently completely different from reptiles, but studies of the genetic building blocks now show that all the hearts have a common molecular structure. The reptilian heart can thus provide us with insight into how the heart works in a human. (Credit: Figure by Bjarke Jensen)
An elaborate system of leads spreads across our hearts. These leads -- the heart's electrical system -- control our pulse and coordinate contraction of the heart chambers. While the structure of the human heart has been known for a long time, the evolutionary origin of our conduction system has nevertheless remained a mystery. Researchers have finally succeeded in showing that the spongy tissue in reptile hearts is the forerunner of the complex hearts of both birds and mammals. The new knowledge provides a deeper understanding of the complex conductive tissue of the human heart, which is of key importance in many heart conditions.
Forerunner of conductive tissue
"The heart of a bird or a mammal -- for example a human -- pumps frequently and rapidly. This is only possible because it has electrically conductive tissue that controls the heart. Until now, however, we haven't been able to find conductive tissue in our common reptilian ancestors, which means we haven't been able to understand how this enormously important system emerged," says Bjarke Jensen, Department of Bioscience, Aarhus University. Along with Danish colleagues and colleagues from the University of Amsterdam, he can now reveal that the genetic building blocks for highly developed conductive tissue are actually hidden behind the thin wall in the spongy hearts of reptiles. The new results have just been published in the journal PLoS ONE.
Different anatomy conceals similarity
"We studied the hearts of cold-blooded animals like lizards, frogs and zebrafish, and we investigated the gene that determines which parts of the heart are responsible for conducting the activating current. By comparing adult hearts from reptiles with embryonic hearts from birds and mammals, we discovered a common molecular structure that's hidden by the anatomical differences," explains Dr Jensen. Since the early 1900s, scientists have been wondering how birds and mammals could have developed almost identical conduction systems independently of each other when their common ancestor was a cold-blooded reptile with a sponge-like inner heart that has virtually no conduction bundles.
Human fetal hearts
The studies show that it is simply the spongy inner tissue in the fetal heart that gets stretched out to become a fine network of conductive tissue in adult birds and mammals. And this knowledge can be put to use in the future. "Our knowledge about the reptilian heart and the evolutionary background to our conductive tissue can provide us with a better understanding of how the heart works in the early months of fetal life in humans, when many women miscarry, and where heart disorders are thought to be the leading cause of spontaneous abortion," says Professor Tobias Wang.
Fact box: Why did we not keep reptilian hearts?
  • Reptiles are cold-blooded animals and therefore have the same temperature as their surroundings. Their spongy hearts are efficient enough to maintain their low metabolism.
  • Birds and mammals -- including humans -- have independently of each other developed a high body temperature (warm-bloodedness) and spend enormous amounts of energy maintaining it. Their pulse has to increase to pump all the blood needed for high metabolism. This means they require efficient conductive tissue in the heart.

Climate Change to Fuel Northern Spread of Avian Malaria: Malaria Already Found in Birds in Alaska

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ScienceDaily (Sep. 19, 2012)Malaria has been found in birds in parts of Alaska, and global climate change will drive it even farther north, according to a new study published September 19 in the journal PLoS ONE.

Researchers at SF State have discovered malaria in birds in Alaska, including the Common Redpoll, above. (Credit: Jenny Carlson, SF State)
The spread could prove devastating to arctic bird species that have never encountered the disease and thus have no resistance to it, said San Francisco State University Associate Professor of Biology Ravinder Sehgal, one of the study's co-authors. It may also help scientists understand the effects of climate change on the spread of human malaria, which is caused by a similar parasite.
Researchers examined blood samples from birds collected at four sites of varying latitude, with Anchorage as a southern point, Denali and Fairbanks as middle points and Coldfoot as a northern point, roughly 600 miles north of Anchorage. They found infected birds in Anchorage and Fairbanks but not in Coldfoot.
Using satellite imagery and other data, researchers were able to predict how environments will change due to global warming -- and where malaria parasites will be able to survive in the future. They found that by 2080, the disease will have spread north to Coldfoot and beyond.
"Right now, there's no avian malaria above latitude 64 degrees, but in the future, with global warming, that will certainly change," Sehgal said. The northerly spread is alarming, he added, because there are species in the North American arctic that have never been exposed to the disease and may be highly susceptible to it.
"For example, penguins in zoos die when they get malaria, because far southern birds have not been exposed to malaria and thus have not developed any resistance to it," he said. "There are birds in the north, such as snowy owls or gyrfalcons, that could experience the same thing."
The study's lead author is Claire Loiseau, a former postdoctoral fellow in Sehgal's laboratory at SF State. Ryan Harrigan, a postdoctoral scholar at the University of California, Los Angeles, provided data modeling for the project. The research was funded by grants from the AXA Foundation and National Geographic.
Researchers are still unsure how the disease is being spread in Alaska and are currently collecting additional data to determine which mosquito species are transmitting the Plasmodium parasites that cause malaria.
The data may also indicate if and how malaria in humans will spread northward. Modern medicine makes it difficult to track the natural spread of the disease, Sehgal said, but monitoring birds may provide clues as to how global climate change may effect the spread of human malaria.

Homolog of Mammalian Neocortex Found in Bird Brain

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ScienceDaily (Oct. 1, 2012) A seemingly unique part of the human and mammalian brain is the neocortex, a layered structure on the outer surface of the organ where most higher-order processing is thought to occur. But new research at the University of Chicago has found the cells similar to those of the mammalian neocortex in the brains of birds, sitting in a vastly different anatomical structure.

Zebra finch. (Credit: © fasphotographic / Fotolia)
The work, published in Proceedings of the National Academy of Sciences, confirms a 50-year-old hypothesis about the identity of a mysterious structure in the bird brain that has provoked decades of scientific debate. The research also sheds new light on the evolution of the brain and opens up new animal models for studying the neocortex.
"If you want to study motor neurons or dopamine cells, which are biomedically important, you can study them in mammals, in chick embryos, in zebrafish. But for these neurons of the cerebral cortex, we could only do that in mammals before," said Clifton Ragsdale, PhD, associate professor of neurobiology at University of Chicago Biological Sciences and senior author of the study. "Now, we can take advantage of these other experimental systems to ask how they are specified, can they regenerate, and other questions."
Both the mammalian neocortex and a structure in the bird brain called the dorsal ventricular ridge (DVR) originate from an embryonic region called the telencephalon. But the two regions mature into very different shapes, with the neocortex made up of six distinct cortical layers while the DVR contains large clusters of neurons called nuclei.
Because of this divergent anatomy, many scientists proposed that the bird DVR does not correspond to the mammalian cortex, but is analogous to another mammalian brain structure called the amygdala.
"All mammals have a neocortex, and it's virtually identical across all of them," said Jennifer Dugas-Ford, PhD, postdoctoral researcher at the University of Chicago and first author on the paper. "But when you go to the next closest group, the birds and reptiles, they don't have anything that looks remotely similar to neocortex."
But in the 1960s, neuroscientist Harvey Karten studied the neural inputs and outputs of the DVR, finding that they were remarkably similar to the pathways traveling to and from the neocortex in mammals. As a result, he proposed that the DVR performs a similar function to the neocortex despite its dramatically different anatomy.
Dugas-Ford, Ragsdale and co-author Joanna Rowell decided to test Karten's hypothesis by using recently discovered sets of molecular markers that can identify specific layers of mammalian cortex: the layer 4 "input" neurons or layer 5 "output" neurons. The researchers then looked for whether these marker genes were expressed in the DVR nuclei.
In two different bird species -- chicken and zebra finch -- the level 4 and 5 markers were expressed by distinct nuclei of the DVR, supporting Karten's hypothesis that the structure contains cells homologous to those of mammalian neocortex.
"Here was a completely different line of evidence," Ragsdale said. "There were molecular markers that picked out specific layers of cortex; whereas the original Karten theory was based just on connections, and some people dismissed that. But in two very distant birds, all of the gene expression fits together very nicely with the connections."
Dugas-Ford called the evidence "really incredible."
"All of our markers were exactly where they thought they would be in the DVR when you're comparing them to the neocortex," she said.
A similar experiment was conducted in a species of turtle, and revealed yet another anatomical possibility for these neocortex-like cells. Instead of a six-layer neocortex or a cluster of nuclei, the turtle brain had layer 4- and 5-like cells distributed along a single layer of the species' dorsal cortex.
"I think that's the interesting part, that you can have all these different morphologies built with the same cell types, just in different conformations," Rowell said. "It's a neocortex or a big clump of nuclei, and then in reptiles they have an unusual dorsal cortex unlike either of those."
Future experiments will test the developmental steps that shape these neurons into various structures, and the relative pros and cons of these anatomical differences. The complex language and tool-use of some bird species suggests that the nuclear organization of this pathway is also capable of supporting advanced functions -- and even may offer advantages over the mammalian brain.
"If you wanted to have a special nuclear processing center in Broca's area to carry out language processing, you can't do that in a mammal," Ragsdale said. "But in a bird they have these special nuclei that are involved in vocalization. It's as if you have additional flexibility: You can have shorter circuits, longer circuits, you can have specialized processing centers."
Beyond the structural differences, the discovery of homologous neocortex cell types will allow scientists to study cortical neurons in bird species such as the chicken, a common model used for examining embryonic development. Such research could help scientists more easily study the neurons lost in paralysis, deafness, blindness, and other neurological conditions.

Local Funding Supports Open Access Sequencing of the Puerto Rican Parrot Genome

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ScienceDaily (Sep. 27, 2012)The critically endangered Puerto Rican Parrot (Amazona vittata) is the only surviving parrot species native to the United States. A genomic sequencing project, funded by community donations, has published September 28, in BioMed Central and BGI's open access journal GigaScience, the first sequence of A. vittata, the first of the large Neotropical Amazona birds to be studied at the genomic level.

The critically endangered Puerto Rican Parrot (Amazona vittata) is the only surviving parrot species native to the United States. (Credit: Image courtesy of BioMed Central Limited)
The Puerto Rican Parrot was once abundant throughout Puerto Rico but destruction of old forest habitats to make way for farming in the 19th Century resulted in a drastic decline in their population. By the mid 1970's only a handful of individuals were thought to remain. Captive breeding programs in Rio Abajo and El Yunque and the release of these birds have had some success, but the number of these birds in the wild is still very low.
In a unique initiative (developing of the Local Community Involvement), funded entirely by contributions from the communities of Puerto Rico alongside staff and students from the Biology Department of the University of Puerto Rico at Mayagüez, researchers collaborated internationally to sequence this beautiful parrot.
Dr Taras Oleksyk, who organized the The Puerto Rican Parrot Genome Project, explained their findings, "In this project we managed to cover almost 76% of the A. vittata genome using money raised in art and fashion shows, and going door to door asking for the support of Puerto Rican people and local businesses. When we compared our sequence of our parrot, Iguaca, from Rio Abajo to other species of birds, we found that she had 84.5% similarity to zebra finches and 82.7% to a chicken, but her genome was highly rearranged."
Dr Oleksyk continued, "We are very proud of our project and even more proud to be part of a local community dedicated to raising awareness and furthering scientific knowledge of this endangered bird. All the data from this project is publically available in GigaDB which we hope will be a starting point for comparative studies across avian genome data, and will be used to develop and promote undergraduate education in genome science in the Caribbean. Community involvement may be the key for the future of conservation genetics, and many projects like this are needed reverse the current rate of extinction of birds across the globe."

Hummingbirds Make Flying Backward Look Easy

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ScienceDaily (Sep. 27, 2012) Backing up usually isn't easy, yet when Nir Sapir observed agile hummingbirds visiting a feeder on his balcony in Berkeley, California, he was struck by their ability to reverse. 'I saw that they quite often fly backwards', he recalls, adding that they always reverse out of a bloom after feasting. However, when he searched the literature he was disappointed to find that there were hardly any studies of this particular behaviour.


Anna's Hummingbird. (Credit: © Melastmohican / Fotolia)
'This was a bit surprising given that they are doing this all the time', Sapir says, explaining that the tiny aviators visit flowers to feed once every 2 min. 'I thought that this was an interesting topic to learn how they are doing it and what the consequences are for their metabolism', Sapir says, so he and his postdoc advisor, Robert Dudley, set about measuring the flight movements and metabolism of reversing hummingbirds and they publish their discovery that reversing is much cheaper than hovering flight and no more costly than forward flight for hummingbirds in The Journal of Experimental Biology.
Capturing five Anna's hummingbirds at a feeder located just inside a University of California Berkeley laboratory window, Sapir trained the birds to fly in a wind tunnel by tricking the birds into feeding from a syringe of sucrose disguised as a flower. He then filmed each bird as it hovered to feed before returning to the perch when satisfied. Knowing that the bird would return to the feeder again soon, Sapir turned on the air flow when the hummingbird arrived, directing the 3 m s flow so that the bird had to fly backwards against the wind to remain stationary at the 'flower'. Then he repeated the experiment with the syringe feeder rotated through 180 deg while the hummingbird flew forward into the wind to stay in place.
Analysing the three flight styles, Sapir recalls that there were clear differences between forward and backward flight. The hummingbirds' body posture became much more upright as they flew backward, forcing them to bend their heads more to insert their beaks into the simulated flower. In addition, the reversing birds reduced the inclination of the plane of the wing beat so that it became more horizontal. And when Sapir analysed the wing beat frequency, he found that the birds were beating their wings at 43.8 Hz, instead of the 39.7 Hz that they use while flying forward. 'That is quite a lot for hummingbirds because they hardly change their wing beat frequency', explains Sapir.
Repeating the experiments while recording the birds' oxygen consumption rates, Sapir says, 'We expected that we would find high or intermediate values for metabolism during backward flight because the bird has an upright body position and this means that they have a higher drag. Also, the birds use backward flight frequently, but not all the time, so we assumed that it would not be more efficient in terms of the flight mechanics compared with forward flight.' However, Sapir was surprised to discover that instead of being more costly, backward flight was as cheap as forward flight and 20% more efficient than hovering. And when Sapir gently increased the wind flow from 0 m s in 1.5 m s steps for a single bird, he found that flight was cheapest at speeds of 3 m s𔂿 and above, although the bird was unable to fly backwards faster than 4.5 m s.
Describing hummingbirds as insects trapped in a bird's body, Sapir adds that the fluttering flight of hummingbirds has more in common with insects than with their feathered cousins and he is keen to find out whether other hovering animals such as small songbirds and nectar-feeding bats can reverse too.

Backpack-Toting Birds Help Researchers Reveal Migratory Divide, Conservation Hotspots

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ScienceDaily (Sep. 25, 2012)By outfitting two British Columbia subspecies of Swainson's thrushes with penny-sized, state-of-the-art geolocators, University of British Columbia researchers have been able to map their wildly divergent migration routes and pinpoint conservation hotspots.

Captured Swainson's thrush wearing a geolocator. (Credit: Kira Delmore, UBC)
"Birds of a feather do not necessarily flock together," says Kira Delmore, a PhD student with UBC's Department of Zoology and lead author of the paper. "Our teams of thrushes took dramatically different routes to get to their wintering grounds, either south along the west coast to Central America, or southeast to Alabama and across the Gulf of Mexico to Columbia."
The study, to be published this week in the Proceedings of the Royal Society of London B, is the first to collect a complete year's worth of data from individual birds to document such a migratory divide.
"This detailed level of migration and stopover data helps us pinpoint vital feeding and rest habitats that the birds rely on at key points during their long journey -- just before crossing the Gulf of Mexico, for example," Delmore adds.
The researchers say the study also raises the possibility that migratory behavior may play a role in speciation, the process by which one species evolves into two.
"Given that migratory behavior is under genetic influence in many species of birds, these results raise the question of what hybrids between these two subspecies would do," says Darren Irwin, associate professor of Zoology at UBC and co-author of the paper. "One possibility is that hybrids would take an intermediate route, leading to more difficulties during migration. If so, the migratory differences might be preventing the two forms from blending into one."
About Swainson's thrushes
Swainson's thrushes, with olive-brown feathers, lighter mottled undersides, and distinct light eye-rings, are typically 16 to 20 centimetres (seven inches) in length with a wingspan of 30 centimetres (one foot). They are not endangered.
Research methodology
UBC researchers caught 40 thrushes in June 2010 -- 20 each of a subspecies from Pacific Spirit Park near UBC in Vancouver and another from locations near Kamloops, B.C. The birds were lured into six-metre-wide mist nets with mating calls.
The geolocators used weigh 0.9 gram and with attachment materials they weight approximately four per cent of the body weight of a thrush.
Researchers then attached the newly invented geolocation devices, which record sunrise and sunset times, on the birds with special harnesses before releasing them. To collect the data, Delmore undertook the process in reverse a year later.
This research was funded by Natural Sciences and Engineering Research Council of Canada, Environment Canada, and the Wilson Ornithological Society.

In Birds' Development, Researchers Find Diversity by the Peck

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ScienceDaily (Sep. 24, 2012) It has long been known that diversity of form and function in birds' specialized beaks is abundant. Charles Darwin famously studied the finches on the Galapagos Islands, tying the morphology (shape) of various species' beaks to the types of seeds they ate. In 2010, a team of Harvard biologists and applied mathematicians showed that Darwin's finches all actually shared the same developmental pathways, using the same gene products, controlling just size and curvature, to create 14 very different beaks.

Greater Antillean bullfinches (Loxigilla violacea) use their deep and wide beaks to crush seeds and hard fruits. Harvard researchers have found that the molecular signals that produce a range of beak shapes in birds show even more variation than is apparent on the surface. (Credit: Photo by José M. Pantaleón)
Now, expanding that work to a less closely related group of birds, the Caribbean bullfinches, that same team at Harvard has uncovered something exciting -- namely, that the molecular signals that produce those beak shapes show even more variation than is apparent on the surface. Not only can two very different beaks share the same developmental pathway, as in Darwin's finches, but two very different developmental pathways can produce exactly the same shaped beak.
"Most people assume that there's this flow of information from genes for development to an inevitable morphology," says principal investigator Arhat Abzhanov, Associate Professor of Organismic and Evolutionary Biology (OEB). "Those beaks are very highly adaptive in their shapes and sizes, and extremely important for these birds. In Darwin's finches, even one millimeter of difference in proportion or size can mean life or death during difficult times. But can we look at it from a bioengineering perspective and say that in order to generate the exact same morphological shape, you actually require the same developmental process to build it? Our latest research suggests not."
The findings have been published in the Proceedings of the National Academy of Sciences.
The Caribbean bullfinches, geographic and genetic neighbors to Darwin's finches, are a group of three similar-looking species that represent two different branches of the evolutionary tree. These bullfinches have very strong bills that are all exactly the same geometric shape but slightly different sizes.
"They specialize in seeds that no one else can touch," explains Abzhanov. "You'd actually need a pair of pliers to crack these seeds yourself; it takes 300 to 400 Newtons of force, so that's a really nice niche if you can do that. But the question is, what developmental changes must have occurred to produce a specialized beak like that?"
A new and highly rigorous genomic analysis by coauthor Kevin J. Burns, a biologist at San Diego State University, has shown that among the three Caribbean bullfinch species, this crushing type of beak actually evolved twice, independently. Convergent evolution like this is common in nature, and very familiar to biologists. But understanding that phylogeny enabled Abzhanov, lead author Ricardo Mallarino (a former Ph.D. student in OEB at the Graduate School of Arts and Sciences), and colleagues in applied mathematics at the Harvard School of Engineering and Applied Sciences (SEAS) to perform a series of mathematical and morphogenetic studies showing that the birds form those identical beaks in completely different ways. Such studies must, by their nature, be performed early in the embryonic stage of the birds' development, when the shape and tissue structure of the beak is determined by the interactions of various genes and proteins.
"In the small bullfinch you have almost a two-stage rocket system," says Abzhanov. "Cartilage takes you halfway, and then bone kicks in and delivers the beak to the right shape. Without either stage, you'll fail. In the larger bullfinches, the cartilage is not even employed, so it's like a single-stage rocket, but it's got this high-energy, synergistic interaction between two molecules that just takes the bone and drives its development straight to the right shape."
In embryos of the small bullfinch, Loxigilla noctis, the control genes used are Bmp4 and CaM, followed by TGFβIIr, β-catenin, and Dkk3, the same combination used in Darwin's finches. Embryos of the larger bullfinches, L. violacea and L. portoricensis, use a novel combination of just Bmp4 and Ihh.
"Importantly," Abzhanov says, "despite the fact that these birds are using different systems, they end up with the same shape beak, and a different shape beak from Darwin's finches. So that reveals a surprising amount of flexibility in both the shapes and the molecular interactions that support them."
The finding offers new insight into the ways birds -- the largest and most diverse group of land vertebrates -- have managed to adaptively fill so many different ecological niches.
"It is possible that even if the beak shape doesn't change over time, the program that builds it does," explains Abzhanov. "For evolution, the main thing that matters for selection is what the beak actually looks like at the end, or specifically what it can do. The multiple ways to build that beak can be continually changing, provided they deliver the same results. That flexibility by itself could be a good vehicle for eventually developing novel shapes, because the developmental program is not frozen."
Following a standard process in studies of developmental biology, Abzhanov's team began with measurements of the morphological differences between species, followed by observations of gene expression in bullfinch embryos and functional experiments using chicken embryos. Along the way, mathematical models helped the team to quantify and categorize the beak shapes they were seeing.
"We used geometric morphometric analysis, looking at these beaks as curves," says coauthor Michael Brenner, Glover Professor of Applied Mathematics and Applied Physics at SEAS and Harvard College Professor. "The beak shapes would turn into contours, contours were digitized into curvatures, and curvatures were turned into representative mathematical formulas. This provided our biology colleagues with an unbiased way of determining which of the different species had beak shapes that were identical up to scaling transformations, and which were in a completely different group."
In order to observe gene expression in the developing bullfinch embryos, Mallarino and a team of undergraduate field assistants had to collect eggs from wild nests in the Dominican Republic, Barbados, and Puerto Rico. The birds breed in dome-shaped nests with small side entrances, often in the tops of tall cacti. In accordance with strict fieldwork regulations, Mallarino's team collected only every third egg laid, which required them to return to the nests daily, climbing dozens of trees and cacti to carefully label every new egg. Laden with radios, notebooks, markers, heavy ladders, and a special foam crate for the delicate eggs, the team ventured into remote field sites at the crack of dawn and returned to camp before noon to incubate those they collected.
"They're much more fragile than a chicken egg, and extremely small," says Mallarino. "We just walk very carefully."
"It's a big logistical operation," he adds. "It's five months of really, really hard work under the sun in crazy conditions, but when it works it's really rewarding. At day 6 or 7 you have a perfect, live embryo with a beak beginning to form, and you can learn so much about it."
The next step in this work is to widen the lens yet again and compare the morphological development of a broader group of birds.
"In time, hopefully we'll see how the great diversity that you see among all these highly adaptive bird beaks may actually evolve at the genetic level," says Mallarino. "That's the greater challenge."
In addition to Abzhanov, Mallarino, and Brenner, coauthors included Otger Campàs, a former postdoctoral associate at the School of Engineering and Applied Sciences (SEAS); Joerg A. Fritz, a graduate student in applied mathematics at SEAS; and Olivia G. Weeks, a graduate student in organismic and evolutionary biology at the Graduate School of Arts and Sciences.
This work was supported by several grants from the National Science Foundation, as well as the Kavli Institute for Bionano Science and Technology at Harvard and the National Institutes of Health.

The Original 'Twitter'? Tiny Electronic Tags Monitor Birds' Social Networks

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ScienceDaily (Sep. 20, 2012) If two birds meet deep in the forest, does anybody hear? Until now, nobody did, unless an intrepid biologist was hiding underneath a bush and watching their behavior, or the birds happened to meet near a research monitoring station. But an electronic tag designed at the University of Washington can for the first time see when birds meet in the wild.

If two birds meet deep in the forest, does anybody hear? Until now, nobody did, unless an intrepid biologist was hiding underneath a bush and watching their behavior, or the birds happened to meet near a research monitoring station. But an electronic tag designed at the University of Washington can for the first time see when birds meet in the wild. (Credit: University of St. Andrews.)
A new study led by a biologist at Scotland's University of St. Andrews used the UW tags to see whether crows might learn to use tools from one another. The findings, published last week in Current Biology, supported the theory by showing an unexpected amount of social mobility, with the crows often spending time near birds outside their immediate family.
The study looked at crows in New Caledonia, an archipelago of islands in the South Pacific. The crows are famous for using different tools to extract prey from deadwood and vegetation. Biologists wondered whether the birds might learn by watching each other.
The results, as reported by St. Andrews, revealed "a surprising number of contacts" between non-related crows. During one week, the technology recorded more than 28,000 interactions among 34 crows. While core family units of New Caledonian crows contain only three members, the study found all the birds were connected to the larger social network.
The new paper is the first published study using the UW tags to record animal social interactions.
"This is a new type of animal-tracking technology," said co-author Brian Otis, a UW associate professor of electrical engineering whose lab developed the tags. "Ecology is just one of the many fields that will be transformed with miniaturized, low-power wireless sensors."
Biologists normally tag animals with radio transmitters that broadcast at a particular frequency, and field researchers use a receiver to listen for that frequency and detect when the animal is present. An encounter between small animals would only be recorded if the researcher was nearby.
The UW system, called Encounternet, uses programmable digital tags that can send and receive pulses.
"Encounternet tags can monitor each other, so you can use them to study interactions among animals," said co-author John Burt, a UW affiliate professor of electrical engineering. "You can't even start to do that with other radio-tracking technology."
Other research groups are using the UW tags around the world. Researchers at the University of Windsor in Canada are using them to study mating behavior in Costa Rican long-tailed manikins; a researcher at Drexel University is using them to study the interaction between birds and army ants in Costa Rica; German researchers are putting the tags on sea lions in the Galapagos Islands to study their behavior as they pull up on beaches; and researchers in the Netherlands are studying the social behavior of great tits, a small woodland bird. "It's a big topic right now, the idea that animals have social networks," Burt said. He has been working with field biologists for the last three years to deploy the tags.
"There are other tags that can do proximity logging, but they're all very big and for larger animals. None is as small as Encounternet -- or even near to it."
The smallest of the UW tags weighs less than 1 gram (0.035 ounces) and can be used on animals as light as 20 grams (less than an ounce), about the weight of a sparrow.
Researchers attach the tags to birds with straps that degrade and harmlessly fall off after the battery dies. The tag records nearby pulses, and the signal strength gives an estimate of the other animal's distance.
A typical study using the system includes a few dozen tags and between 10 and 100 fixed base stations. When tagged animals pass a base station the data is transmitted wirelessly from the tag to the base station, and from there to the Internet. Researchers can also reprogram the tags remotely -- for example, they can look at initial results to see when there are few encounters happening, and turn the battery off during those times to conserve power.
Burt completed his doctorate at the UW in 2000, with a dissertation on birdsong communication and learning. He wished that there was a way to automatically monitor bird interactions in the wild, and in 2005 joined forces with Otis, an expert in small, lightweight, low-power electronics. Burt managed the project to develop the tags, with funding from the National Science Foundation, as a research scientist in Otis' group. This fall they founded Encounternet LLC in Portland, Ore., where Burt now lives. He is working to add a GPS component to record the location of encounters, and to add an accelerometer and other sensors that could detect an animal's behavior.
"People are excited about this because for the first time, it allows them to study smaller animal interactions and social networks on an incredibly fine scale," Burt said. "Social networks are turning out to be key to understanding many animal behaviors. People say Encounternet is the only thing they can find that can collect that information."

How Birds Master Courtship Songs: Zebra Finches Shed Light On Brain Circuits and Learning

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ScienceDaily (Sep. 17, 2012) By studying how birds master songs used in courtship, scientists at Duke University have found that regions of the brain involved in planning and controlling complex vocal sequences may also be necessary for memorizing sounds that serve as models for vocal imitation.

Zebra finch. (Credit: © jurra8 / Fotolia)
In a paper appearing in the September 2012 issue of the journal Nature Neuroscience, researchers at Duke and Harvard universities observed the imitative vocal learning habits of male zebra finches to pinpoint which circuits in the birds' brains are necessary for learning their songs.
Knowing which brain circuits are involved in learning by imitation could have broader implications for diagnosing and treating human developmental disorders, the researchers said. The finding shows that the same circuitry used for vocal control also participates in auditory learning, raising the possibility that vocal circuits in our own brain also help encode auditory experience important to speech and language learning.
"Birds learn their songs early in life by listening to and memorizing the song of their parent or other adult bird tutor, in a process similar to how humans learn to speak," said Todd Roberts, Ph.D., the study's first author and postdoctoral associate in neurobiology at Duke University. "They shape their vocalizations to match or copy the tutor's song."
A young male zebra finch, Roberts said, learns his song in two phases -- memorization and practice. He said the pupil can rapidly memorize the song of an adult tutor, but may need to practice singing as many as 100,000 times in a 45-day period in order to accurately imitate the tutor's song.
During the study, voice recognition software was paired with optogenetics, a technology that combines genetics and optics to control the electrical activity of nerve cells, or neurons. Using these tools, the researchers were able to scramble brain signals coordinating small sets of neurons in the young bird's brain for a few hundred milliseconds while he was listening to his teacher, enabling them to test which brain regions were important during the learning process.
The study's results show that a song pre-motor region in the pupil's brain plays two different roles. Not only does it control the execution of learned vocal sequences, it also helps encode information when the pupil is listening to his tutor, Roberts said.
"We learn some of our most interesting behaviors, including language, speech and music, by listening to an appropriate model and then emulating this model through intensive practice," said senior author Richard Mooney, Ph.D., professor of neurobiology and member of the Duke Institute for Brain Sciences. "A traditional view is that this two-step sequence -- listening followed by motor rehearsal -- first involves activation by the model of brain regions important to auditory processing. This is followed days, weeks or even months later by activation of brain regions important to motor control."
"Here we found that a brain region that is essential to the motor control of song also has an essential role in helping in auditory learning of the tutor song," Mooney said. "This finding raises the possibility that the premotor circuits important to planning and controlling speech in our own brains also play an important role in auditory learning of speech sounds during early infancy." This brain region, known as Broca's area, is located in the frontal lobe of the left hemisphere.
The research has implications for the role of premotor circuits in the brain and suggests that these areas are important targets to consider when assessing developmental disorders that affect speech, language and other imitative behaviors in humans, Roberts said.
In addition to Roberts and Mooney, study authors include Sharon M. H. Gobes of Harvard University and Wellesley College; Malavika Murugan of Duke; and Bence P. Ölveczky of Harvard.
The research was supported by grants from the National Science Foundation and the National Institutes of Health (R01 DC02524) to Richard Mooney; and grants from NIH (R01 NS066408) and the Klingenstein, Sloan and McKnight Foundations to Bence P. Ölveczky; and a Rubicon fellowship from the Netherlands Organization for Scientific Research to Sharon M.H. Gobes.

Canadian Homes a Kill Zone for Up to 22 Million Birds a Year, Researchers Estimate

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ScienceDaily (Sep. 14, 2012)The thud of a bird hitting a window is something many Canadian home owners experience. Up until now, little research has been done to document the significant these collisions for Canada's bird populations. A University of Alberta biology class project supervised by researcher Erin Bayne suggests that many birds meet their end in run-ins with Canadian homes.

Cardinal. The thud of a bird hitting a window is something many Canadian home owners experience. (Credit: © Chris Hill / Fotolia)
The U of A students estimate a staggering 22 million birds a year die from colliding with windows of homes across the country.
The research was done in Edmonton and surrounding area using evidence gathered from more than 1,700 homeowners. Homeowners were recruited to become citizen scientists for the study. The citizen scientists were required to complete an online survey where they were asked to recall fatal bird hits over the previous year.
Bayne and his team processed the Edmonton data and concluded that with approximately 300,000 homes in the study area the death toll for birds from window strikes might reach 180,000 per year.
The researchers applied that figure to national housing statistics and arrived at the 22 million figure for bird vs. window fatalities. Bayne says that many people recalled bird strikes at their homes, but there was little awareness that residential window deaths might affect bird populations.
The main factors influencing the frequency of bird -- window collisions were the age of the trees in the yard and whether or not people fed birds.
"In many cases people who go out of their way to help birds by putting up feeders and bird friendly plants are unwittingly contributing to the problem," said Bayne.
One tip the researchers have for the safer placement of a bird feeder concerns its distance from the house. Bayne says the safety factor has to do with a bird's flying speed. As with car crashes; speed kills.
"A feeder three to four metres from a window is bad because the bird has space to pickup lots of speed as it leaves the feeder," said Bayne.
Fast-flying birds like sparrows and chickadees and aggressive birds like robins are apt to collide with windows placed too close to free food.
Placing the feeder either closer or much further are options.
Researchers believe many window collisions are caused by in-flight mistakes. "It's called a panic flight; a bird startled by a cat or competing with other birds at the feeder may suddenly take flight and doesn't recognize the window as a hazard" said Bayne.
The research was published in the journal Wildlife Research.