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The official blog of ornithology journals The Auk and The Condor
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Nesting in Cavities Protects Birds from Predators—to a Point

Thu, 07/13/2017 - 12:00

A Marsh Tit brings nesting material to a cavity. Photo credit: M. Arndt

Nesting in cavities provides birds with some protection from predators—but it isn’t foolproof. A new study from The Auk: Ornithological Advances explores how Poland’s cavity-nesting Marsh Tits deal with predator attacks and finds that while tactics such as small entrances and solid walls do help, adaptations like this can only take the birds so far.

Wrocław University’s Tomasz Wesołowski has spent nearly thirty years monitoring Marsh Tit nest cavities in Poland’s Białowieża Forest, comparing nests that are destroyed with nests that are attacked but survive. He has found that a nest’s chance of survival depends on the predator’s technique—broods are least likely to survive (10%) when the predator manages to get into the cavity through the existing entrance, more likely (29%) when the predator uses its paws or beak to pluck out the nest contents, and most likely to survive (39%) when the predator tries to enlarge the opening or make a new one. Tits’ antipredator tactics vary in their effectiveness depending on the predator; attacks by Great Spotted Woodpeckers were successful only 60% of the time, while forest dormice were 100% successful.

The results show that despite the constant pressure of natural selection, Marsh Tits can only improve their antipredator tactics so much—there are limits to adaptation. Small, narrow entrances don’t work against small predators and are only effective when combined with cavity walls made of solid (not decomposing) wood; nests that were deep in a cavity, out of reach of the entrance, are safest, but birds seldom place their nests that way, suggesting that cavities that are too deep may cause other problems for Marsh Tit parents.

The Białowieża Forest, one of the last remaining tracts of old-growth forest in Europe, is an ideal place to study cavity-nesting birds, full of cavities of every size and shape for Marsh Tits to choose from. However, the fieldwork was not without its difficulties. “The Białowieża Forest still contains fragments of primeval origin,” says Wesołowski. “The work is challenging, as the old-growth stands are very tall. Marsh Tits breed at very low densities, and on average one has to search five to seven hectares of this forest to find a single breeding cavity. It requires much patience and determination.”

“To understand the evolution of nesting behaviors, many ornithologists attempt to quantify the trade-offs that birds face in warding off nest predators. Usually we do this by comparing nests that fail versus nests that succeed, but that approach is limited because we can’t tease apart the multiple factors, including chance, that contributed to making a nest successful,” according to Kristina Cockle of the National Scientific and Technical Research Council of Argentina (CONICET), an ornithologist not involved with the study who has worked extensively on nest cavities. “The new study by Wesołowski compares, instead, nests that were depredated to nests that were attacked but survived. With this approach, the author was able to identify the physical attributes of tree cavities that foiled a suite of nest attackers from woodpeckers to dormice.”

Failed predator attacks: A study of tree cavities used by nesting Marsh Tits (Poecile palustris) for security is available at http://www.bioone.org/doi/full/10.1642/AUK-17-51.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


Seaside Sparrows Caught Between Predators and Rising Seas

Thu, 07/13/2017 - 12:00

Fledgling Seaside Sparrows. Photo credit: E. Hunter

Sea-level rise may be a big problem for salt marsh birds, but so is predation, and birds sometimes find themselves caught between a rock and a hard place: They can place their nests lower in the vegetation to avoid predators, putting them at greater risk of flooding, or move them up to keep them dry but risk getting eaten. A new study from The Condor: Ornithological Applications finds that greater pressure from predators increases the risk of flooding for Seaside Sparrow nests—but the upside is that protecting them from predators could also mitigate the worst effects of climate change.

The University of Georgia’s Elizabeth Hunter (now at the University of Nevada–Reno) created a mathematical model to simulate Seaside Sparrow’s nesting behavior and success rates, based on nesting data collected on the coast of Georgia.  Her model shows that predation risk has had a much greater effect than flooding risk on nest survival rates. While flooding risk had essentially no effect on predation rates over this time period, predation risk did affect flooding rates—that is, because birds moved their nests down to avoid predators, they increased their risk of flooding. Under future sea level rise scenarios, flooding risk increases, but predation risk is still almost seven times as important for determining nest survival rates.

“Nest predation rates are so high right now that even under extreme sea level rise conditions, more nests are likely to be eaten than flooded,” says Hunter. “However, predation and flooding threats act synergistically, meaning that any estimates of the negative effects of sea level rise on the nesting success of Seaside Sparrow or other species are likely underestimates if they do not also consider the negative effects of predation on flooding risk. The flip side of this is that management actions to reduce nest predation could also reduce the risk of nest failures from flooding.” If measures such as fencing nest sites to exclude predators are taken, birds may place their nests higher in the salt-marsh vegetation, avoiding flooding from extreme high tides.

“Elizabeth Hunter’s research highlights both the risks that sea-level rise poses for coastal wildlife and the complexity of understanding those risks in light of other threats to their survival,” according Chris Elphick of the University of Connecticut, an expert on tidal marsh birds who was not involved with the study. “The study nicely illustrates the importance of understanding the behavior of individual birds when trying to devise strategies to mitigate threats such as predation and tidal flooding. Regardless of the threat, it is increasingly clear that tidal marsh birds and their habitats are in trouble, and that we need to explore a range of potential solutions to find ways to help them persist in light of the many ways that humans are changing coastal habitats.”

How will sea-level rise affect threats to nesting success for Seaside Sparrows? is available at http://www.bioone.org/doi/abs/10.1650/CONDOR-17-11.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


Ornithology & Social Media – A Perfect Partnership

Mon, 07/03/2017 - 09:44

This blog is one of the ways that the publications staff behind The Auk and The Condor connects with the journals’ readers (a.k.a. you!). Another? Social media.

Each journal has its own Twitter account (@AukJournal and @CondorJournal), where we share the latest ornithology research—from other publications as well as our own—and news that’s relevant to our community. The American Ornithological Society, our parent organization, also uses social media—in addition to Twitter, they’re on Facebook and Instagram. You don’t need an account on any of these sites to read the content posted there, and checking them out periodically will help you keep up with the latest developments in the American ornithology world.

If you’re interested in learning more about social media, whether you’re an avid user looking to get some new tips or you’re thinking of wading in for the first time, you should consider attending the social media symposium at American Ornithology 2017, the joint annual meeting of AOS and SCO (the Society of Canadian Ornithologists) that’s coming up in Michigan. The symposium begins at 10 a.m. on Wednesday, August 2, and will cover how using social media for science communication can benefit your research and your career. Hope to see you there!


Birds’ Feathers Reveal Their Winter Diet

Wed, 06/21/2017 - 10:45

A freshly molted Bobolink. Photo credit: R.M. Jensen

Influences outside the breeding season can matter a lot for the population health of migratory birds, but it’s tough to track what happens once species scatter across South America for the winter months. A study from The Condor: Ornithological Applications tries a new approach for determining what declining migratory grassland birds called Bobolinks eat after they head south for the winter—analyzing the carbon compounds in their plumage, which are determined by the types of plants the birds consume while growing their feathers during their winter molt.

Thanks to a quirk of photosynthesis, rice contains a different ratio of carbon isotopes than most of the native grasses in South America where Bobolinks winter. Rosalind Renfrew of the Vermont Center for Ecostudies and her colleagues took advantage of this, collecting feather samples from wintering Bobolinks in a rice-producing region and a grassland region and from breeding Bobolinks in North America. When they analyzed the feathers’ isotopes ratios, the results from South America confirmed that isotopes in Bobolinks’ feathers reflected the differences in their diets between regions with and without rice production. The samples taken in North America showed that the winter diet of most individuals was weighted more toward non-rice material, but that rice consumption was highest late in the winter, when rice is nearing harvest and the birds are preparing for their northbound migration.

Rice could be beneficial by providing the birds with needed calories as they prepare for their journey north, but it could also increase Bobolinks’ exposure to pesticides and threats from farmers who see them as pests. According to Renfrew and her colleagues, maintaining native grasslands, encouraging integrated pest management programs to reduce toxic pesticide applications, and compensating farmers for crops lost to feeding birds all would be helpful.

“The time spent coordinating the field work for this study may well have been greater than the time spent collecting the data,” says Renfrew. “It was truly a team effort, and the assistance we received from our partners was absolutely essential, especially in South America. Aves Argentinas and the Museo de Historia Natural de Noel Kempff Mercado provided priceless logistical support, and this study could not have happened without them. Some of the same partners have provided input on a Bobolink Conservation Plan that lays out actions to address threats to grassland birds in North and South America, based on results from this and other studies.”

“As Bobolink populations continue to decline, Renfrew and her colleagues use state-of-the-art isotope analysis techniques to assess the Bobolink’s diet on its South American wintering grounds,” according to John McCracken of Bird Studies Canada, an expert on grassland bird conservation who was not involved with the study. “The authors conclude that rice may have negative effects on Bobolinks, owing to its relatively low nutritional quality and from exposure to insecticides.”

Winter diet of Bobolink, a long-distance migratory grassland bird, inferred from feather isotopes is available at http://www.bioone.org/doi/full/10.1650/CONDOR-16-162.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


2016 Journal Impact Factors Released

Tue, 06/20/2017 - 16:19

The 2016 impact factors for peer-reviewed journals were released last week, and both journals published by the American Ornithological Society saw a boost in their numbers—The Condor is up to 2.654 from 1.427 and is now #1 of the 24 ornithology journals ranked, and The Auk is up to 2.096 from 1.871 (ranking #4). This means that the American Ornithological Society now publishes half of the top four ornithology journals in the world.

Impact factors are calculated based on the number of citations received in a year by articles published in a journal during the two preceding years and are considered to be an important measure of a journal’s prominence in its field. The AOS publications team wants to thank all of our Associate Editors, authors, and reviewers, as well as everyone who reads and cites The Auk and The Condor!


Muscle Fibers Alone Can’t Explain Sex Differences in Bird Song

Wed, 06/14/2017 - 12:56

Male birds tend to be better singers than females—but does the basis for this difference lie in the brain or in the syrinx, the bird equivalent of our larynx? The researchers behind a new study from The Auk: Ornithological Advances analyzed the muscle fibers in the syrinxes of male and female birds from a range of species and found, to their surprise, that the amount of “superfast” muscle wasn’t typically related to differences in vocal ability between the sexes.

Most muscle fibers are one of two types—fast, specialized for short, intense bursts of activity, or slow, specialized for endurance. However, some animals, including birds, have a third type called superfast muscle that can contract around 200 times per second. Ron Meyers of Weber State University and his colleagues hypothesized that superfast muscle fibers in the syrinx might explain the greater singing ability of male birds, but when they analyzed the syringeal muscles of male and female birds from a range of species, they found that the amount of superfast muscle fiber didn’t differ between the sexes in most species. Instead, their results suggest that the role of superfast muscle is more complicated than they expected and may be related to the entire range of vocalizations of a species rather than song alone. Even though females of some species don’t sing, their superfast muscle fibers appear likely to play a role in the calls they use for other types of communication.

The researchers collected syringeal tissue from a total of ten bird species, some wild-caught and some from a University of Utah aviary. All species had both fast muscle and superfast muscle fiber in their syrinxes, but there was a clear sex difference in fiber type composition in only two species studied, Bengalese Finches and Zebra Finches. Based on this, the researchers speculate that the need for superfast muscle may be related to the entire vocal repertoire of each sex, not just singing behavior. Calls made by Zebra Finch females don’t have acoustic features that would require rapid muscle control, but in other species females may produce calls that require the muscle control provided by superfast fibers even if they don’t sing.

“The data really surprised us,” says Meyers. “Based on our first species studied, starlings and Zebra Finches, we went into this thinking that superfast fibers were related to singing in males. Zebra Finch males sing and females don’t, and males have 85% of the syrinx muscles made up of superfast fibers. In starlings, both male and females sing, and they both had about a 65% make-up of superfast fibers. But as the number of species we looked at grew, we had to totally change our perception of the role of superfast fibers in singing and the role they actually play in vocalizing.”

“Most of the research investigating the mechanisms of bird song focuses on the brain. However, research has begun to suggest that peripheral structures like the syrinx influence song divergence, which of course is an important factor that contributes to avian biodiversity,” according to Wake Forest University’s Matthew Fuxjager, an expert on superfast muscle. “This study therefore provides an exciting starting point to address this issue from a physiological perspective, and it shows that muscle fiber content in the syrinx might not be a strong predictor of avian vocal diversity. But then what is? I would argue that we’re still working this out, and that this study will provide an intriguing framework from which more work in this area can be conducted.”

Is sexual dimorphism in singing behavior related to syringeal muscle composition? is available at http://www.bioone.org/doi/full/10.1642/AUK-17-3.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


Radar Reveals Steep Declines in Kauai’s Seabird Populations

Wed, 06/07/2017 - 16:53

A Newell’s Shearwater chick in a burrow. Photo credit: A. Raine

The island of Kauai is home to two endangered seabirds, the Hawaiian Petrel and the Newell’s Shearwater. Monitoring these birds, which are nocturnal and nest in hard-to-access areas, is challenging, but observing the movements of birds via radar offers a solution. A new study from The Condor: Ornithological Applications takes a fresh look at two decades of radar data—and comes to worrying conclusions about the status of both species.

To assess the population trends and distribution of the birds in recent decades, André Raine of the Kauai Endangered Seabird Recovery Project and his colleagues examined past and contemporary radar surveys as well as data on the numbers of shearwater fledglings rescued after being attracted to artificial lights. Their results shows continuing population declines in both species over the last twenty years—a 78% reduction in radar detections for Hawaiian Petrels and a 94% reduction for Newell’s Shearwaters, with the shearwater decline mirrored in decreasing numbers of recovered fledglings over time.

For shearwaters, this is consistent with previously published work, but past analyses of petrel radar data suggested their population was stable or potentially increasing. The researchers attribute the difference to the fact that for this new study, they carefully standardized the data based on sunset times, which ensured that the time periods (and thus bird movement periods) under consideration remained constant from the beginning to the end of the survey period. They believe that the steep declines may have commenced in earnest in the aftermath of Hurricane Iniki in 1992, which led to permanent ecological changes such as the opening of new routes for invasion by exotic predators and plants, as well as significant infrastructure changes across the island.

“These seabirds face a wide range of threats,” says Raine. “Conservation effort needs to be focused on reducing power line collisions, fall-out related to artificial lights, the control of introduced predators, and the overall protection of their breeding habitats. Many of these efforts are now underway on Kauai, and I am hopeful that these will continue and expand over the next few years. Ultimately, the conservation of the breeding grounds of endangered seabirds on Kauai is actually the conservation of our native forests and watersheds, with far-reaching benefits for other native plants and birds that rely on these habitats, as well as—ultimately—ourselves.”

“It is important to publish this information so that everyone can better understand the severity of the declines in these species and the threats they face,” agrees Pacific Rim Conservation’s Eric VanderWerf, an expert on Hawaiian seabirds. “We need to consider these data in order to make informed decisions about the best conservation measures.”

Declining population trends of Hawaiian Petrel and Newell’s Shearwater on the island of Kaua’i, Hawaii, USA is available at http://americanornithologypubs.org/doi/abs/10.1650/CONDOR-16-223.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


Which Extinct Ducks Could Fly?

Wed, 06/07/2017 - 16:47

Fossils of extinct ducks and geese provide new clues about flightlessness. Photo credit: J. Watanabe

We’re all familiar with flightless birds: ostriches, emus, penguins—and ducks? Ducks and geese, part of a bird family called the anatids, have been especially prone to becoming flightless over the course of evolutionary history. However, it can be difficult to determine from fossils whether an extinct anatid species could fly or not. A new study from The Auk: Ornithological Advances takes a fresh approach, classifying species as flightless or not based on how far their skeletal proportions deviate from the expected anatomy of a flying bird and offering a glimpse into the lives of these extinct waterfowl.

Kyoto University’s Junya Watanabe painstakingly measured 787 individual birds representing 103 modern duck and goose species. From this data, he developed a mathematical model that was able to separate flightless and flying species based on their wing and leg bones—flightless species, the math confirmed, have relatively small wings and relatively large legs. Applying the model to fossil specimens from 16 extinct species identified 5 of the species as flightless, ranging from a land-dwelling duck from New Zealand to a South American duck that propelled itself underwater with its feet.

“I really enjoyed measuring bones in museums and appreciate the hospitality given to me by museum staff. One of the most exciting things was to find interesting fossils that were previously unidentified in museum drawers,” says Watanabe. “What is interesting in fossil flightless anatids is their great diversity; they inhabited remote islands and continental margins, some of them were specialized for underwater diving and others for grazing, and some were rather gigantic while others were diminutive.”

“Dr. Watanabe has developed a valuable statistical tool for evaluating whether a bird was capable of powered flight or not, based on measurements of the lengths of only four different long bones. His method at present applies to waterfowl, but it could be extended to other bird groups like the rails,” according to Helen James, Curator of Birds at the Smithsonian Institution’s National Museum of Natural History. “Other researchers will appreciate that he offers a way to assess limb proportions even in fossil species where the bones of individual birds have become disassociated from each other. Disassociation of skeletons in fossil sites has been a persistent barrier to these types of sophisticated statistical analyses, and Dr. Watanabe has taken an important step towards overcoming that problem.”

Quantitative discrimination of flightlessness in fossil Anatidae from skeletal proportions is available at http://americanornithologypubs.org/doi/full/10.1642/AUK-17-23.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


AUTHOR BLOG: Tracking Yosemite’s Spotted Owls

Wed, 05/31/2017 - 12:14

Tracking Spotted Owls in Yosemite National Park. Photo credit: S. Scherbinski

Stephanie Eyes

Linked paper: California Spotted Owl (Strix occidentalis occidentalis) habitat use patterns in a burned landscape by S.A. Eyes, S.L. Roberts, and M.D. Johnson, The Condor: Ornithological Applications 119:3, August 2017.

In 2005, I happily discovered the Student Conservation Association and that I could be an intern studying California Spotted Owls in Yosemite National Park. I accepted the internship and worked on a PhD student’s project investigating the effects of fire on California Spotted Owl occupancy. The final results from this study revealed that owl occupancy rates were similar between burned and unburned forest, but led to questions about how owls use the mosaic of post-fire patches. In 2010, the former PhD student, my graduate advisor, and I began our efforts to understand this question by capturing owls and affixing radio transmitters to them with the help of several technicians over the course of the three field seasons. By attaching a radio transmitter, we were able to use radio telemetry to triangulate the position of owls during nocturnal foraging bouts. Specifically, we wanted to know how owl foraging patterns are influenced by fire severity, fire-created edges, and other factors such as topography or distance to stream or nest/roost site.

After owls were captured, we set up our telemetry stations along the trails and roads surrounding our known owl roost sites. We went out in teams of two, each armed with a headlamp and an antenna, and worked to locate the owls within our burned sites. Once we initially identified that an owl was present with our antenna, we would split up, one person racing ahead so that we could get three different readings within ten minutes, each separated by about 200 meters, before the owl moved to a new foraging site. While I was relatively experienced with daytime radio telemetry, these nocturnal trail surveys posed a new challenge I enjoyed overcoming, and one time we encountered a curious mountain lion also using the trail searching for (I hoped!) something else.

Whenever we surveyed these trail sites, I remember wondering what the owl was hunting in the burned mosaic of forest patches at the moment that we were trying to pinpoint its location. I’m hoping all my wondering what they were eating will encourage me to go through all the pellets we found in burned forests!

After all the data was collected and analyzed, we learned that owls exhibited habitat selection for locations near roosts and edge habitats, as well as weak selection for lower fire severities. Our results highlight the importance of sustaining forests burned with a mosaic of fire severities with smaller patch sizes of high severity fire. Maintaining this complex mosaic of forest patches and focusing on protecting roost site locations may help sustain California Spotted Owls in the greater landscape.


Spotted Owls Benefit from Forest Fire Mosaic

Wed, 05/31/2017 - 12:13

California Spotted Owls use a mosaic of fire-created habitat. Photo credit: S. Eyes

Fire is a crucial part of the forest ecosystem on which threatened Spotted Owls rely, but climate change and decades of fire suppression are changing the dynamics of these forests. A new study from The Condor: Ornithological Applications examines California Spotted Owl habitat use in Yosemite National Park and shows that while owls avoid the badly burned areas left behind by massive stand-replacing fires, they benefit from habitat that includes a mosaic of burned patches of different sizes and degrees of severity.

The National Park Service’s Stephanie Eyes (formerly of Humboldt State University) and her colleagues wanted to know how Spotted Owl foraging patterns are influenced by fire severity and fire-created edges, with the goal of informing future fuels reduction efforts and prescribed burning programs. They used radio-transmitters to track movements of 13 owls on eight territories in Yosemite National Park between 2010 and 2012 and found that overall, owls foraged near their roosts and along the edges of patches of burned forest, preferring these edge habitats. Owls selected larger burned patches than the average available size but avoided the interiors of severely burned patches.

“Maintaining a complex mosaic of forest patches with smaller patches of high severity fire can help sustain California Spotted Owls in the greater landscape,” says Eyes. “What’s unique about our study is that we investigated fires that burned within the natural range of variation, so it paints a picture of how owls used a burned landscape before the onset of today’s large stand-replacing fires.” Despite the owls’ preference for edges, there may be a threshold over which edges have a negative effect on habitat quality, and more research is needed to find the right balance between beneficial edge habitat and potentially harmful habitat fragmentation.

“This paper provides new radio telemetry data on how owls use home ranges that have had recent wildfires,” according to the University of Minnesota’s R.J. Gutiérrez, an expert on Spotted Owl habitat use. “Eyes and her colleagues provide a new piece of the puzzle about how owls respond, and they show that this response can be complex. More importantly, because their work occurred within a national park, it will serve as a ‘natural control’ that can be compared with other owl–fire studies occurring on managed forests.”

California Spotted Owl (Strix occidentalis occidentalis) habitat use patterns in a burned landscape is available at http://americanornithologypubs.org/doi/abs/10.1650/CONDOR-16-184.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


New Details on Nest Preferences of a Declining Sparrow

Wed, 05/31/2017 - 12:12

A Bachman’s Sparrow. Photo credit: J. Winiarski

Theory says that birds should choose nest sites that minimize their risk of predation, but studies often fail to show a connection between nest site selection and nest survival. Understanding these relationships can be key for managing declining species, and a new study from The Condor: Ornithological Applications explores the nest site preferences of Bachman’s Sparrow, a vulnerable songbird dependent on regularly burned longleaf pine forests in the southeastern U.S.

Jason Winiarski of North Carolina State University and his colleagues monitored a total of 132 Bachman’s Sparrow nests in two regions of North Carolina, the Coastal Plain and the Sandhills, measuring a variety of vegetation characteristics. They found several differences between the two regions in what sparrows looked for in a nest site—in the Coastal Plain, they favored low grass density and greater woody vegetation density, while birds in the Sandhills selected intermediate grass density and greater tree basal area. However, none of these features turned out to be related to nest survival.

According to the researchers, the differences between the two regions are likely due to differences in the available plant communities. Bachman’s Sparrows also could be selecting nest sites that allow easy access to nests or maximize the survival of fledglings once they leave, and these aspects may warrant further investigation. Regardless, Winiarski and his colleagues believe their results show the importance of management that mimics historical fire regimes in longleaf pine ecosystems, in order to maintain the diverse groundcover types used by the birds.

The most challenging part of the study was locating sparrow nests to monitor. “Bachman’s Sparrows are notoriously secretive and don’t easily give up the location of their well-hidden nests,” says Winiarski. “Eventually, we stumbled upon a technique of patiently watching adult sparrows at a distance that allowed the birds to behave normally, while being close enough for us to just barely see where they landed with food or nest material. That let us narrow down where the nest site was to within a few meters, and luck and thorough searching led us the rest of the way.”

“It is really remarkable that the authors were able to track the large number of Bachman’s Sparrow nests that they were able to find. As someone who has searched and searched for nests of this species, it is really hard,” according to Purdue University’s John Dunning, an expert on Bachman’s Sparrow ecology who was not involved with the research. “The study shows how consistent management of vegetation structure through the use of prescribed fire remains the most important management and conservation strategy to support breeding populations of Bachman’s Sparrow.”

Nest-site selection and nest survival of Bachman’s Sparrows in two longleaf pine communities is available at http://americanornithologypubs.org/doi/abs/10.1650/CONDOR-16-220.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


AUTHOR BLOG: ‘Bare Parts’ are an Important but Underappreciated Avian Signal

Wed, 05/24/2017 - 10:26

Two female American Goldfinches in an antagonistic interaction. Bill-color, derived from carotenoids, is a signal of dominance among female goldfinches but not among males. Image credit: K. Tarvin

Erik Iverson

Linked paper: The role of bare parts in avian signaling by E.K. Iverson and J. Karubian, The Auk: Ornithological Advances 134:3, July 2017.

Birds are well-known for being among the most colorful of all animals, with many species displaying striking, brightly-colored feathers. Scientists have long wondered why color is so important to fitness, and hundreds of studies have been published on the relationships between plumage and traits such as age, physiological condition, reproductive success, and attractiveness to mates. However, there is a growing awareness that plumage is not the only important site of coloration among birds; there is also considerable variation within and between species in the color of bills and in bare skin such as legs, feet, ceres, or wattles. Yet compared to plumage, these ‘bare part’ ornaments have received relatively little attention; a 2006 review of carotenoid coloration in birds, for instance, identified only 14 studies of bare parts versus 130 studies of plumage.

Unlike plumage, bare part color has the potential to be highly flexible. For example, carotenoid-based bare parts can lose their color within days of food deprivation or within hours of stress. Amidst growing suggestions that changes in bare part color could have important implications for signaling, one of the authors, Jordan Karubian, was studying Red-Backed Fairywrens (Malurus melanocephalus) in Australia. In this species, males either acquire a territory and display black breeding plumage and bills, or stay dull and serve as helpers at the nest. Jordan noticed that when a breeding male died and a dull male took over its vacancy, the dull male’s bill would darken within several weeks. Experiments confirmed this effect and showed that dull males with newly black bills also had testosterone levels comparable to birds with black plumage. I joined Jordan’s lab as an undergraduate and studied fairywrens as well, and when I was looking for a topic for an honors thesis Jordan suggested that bare parts were an expanding area in need of a review. That thesis grew and grew, eventually becoming my master’s work and encompassing 321 published studies of bare-part coloration and signaling.

Our review shows that despite the research focus on plumage, bare part signals might be more common than plumage-based ones and are an important visual signal in many species that lack bright plumage altogether. Carotenoids, melanin, and structural colors are all flexible in bare parts, and rapid blood flushing through skin can change color even more rapidly. Bare part color provides up-to-date information about a signaler, allowing competitors, mates, and offspring to adjust their strategies and maximize their fitness. Carotenoid-signaling with bare parts may also be less costly than with plumage, allowing signaling by females and non-breeding males. In species where both plumage and bare parts of the same color exist, the two are likely to be ‘multiple messages,’ conveying different aspects of condition or targeting different audiences. We believe that more careful and extensive characterization of bare part coloration will contribute greatly to our understanding of this underappreciated dynamic signal, and help inform a more inclusive theory of animal communication.


Song Diversity Hints at Thrushes’ Evolutionary Past

Wed, 05/24/2017 - 09:50

A spectrogram of a Hermit Thrush song shows the introductory note (at left) and the more complex song that follows.

The Hermit Thrush is famous for its melodiously undulating song, but we know very little about whether—and if so, how—its songs vary across the large swath of North America that it calls home in the summer. A new study from The Auk: Ornithological Advances provides the first thorough overview of geographic variation in Hermit Thrush song structure and hints at how isolation and adaptation shape differences in the tunes of a learned song within a species.

Sean Roach and Leslie Phillmore of Nova Scotia’s Dalhousie University gathered recordings of Hermit Thrush songs from a number of databases, accumulating a sample of 100 individuals recorded across North America between 1951 and 2015. Spectrographic analysis revealed significant differences in song structure across the three major populations—Northern, Western Mountain, and Western Lowland—as well as within them. The most striking differences were in the pitch of the introductory notes that preface the birds’ songs, with Western Lowland thrushes producing higher, more variable introductory notes than their relatives elsewhere.

“Though Hermit Thrushes have a beautiful, well-known song, relatively little is known about their singing behavior,” says Roach. “Knowing how the species varies with respect to genetics and morphology, I became interested in how their song varies, as song can play an important role in processes like speciation.” Some of the variation the researchers found likely dates back to isolation of different Hermit Thrushes populations by ice sheets during the Pleistocene era, while differences between the two western groups may relate to body size, with larger birds producing lower-frequency songs. One group of high-altitude birds in the Canadian Rockies sang songs that stood out other members of their subspecies, which Roach and Phillmore believe is an adaptation to how sound carries in their open, shrubby habitat.

“Genetic studies of Hermit Thrushes in North America have defined three different groups of subspecies, with major splits most likely occurring as a consequence of two glaciation events. Roach and Phillmore show convincingly that these three major groups of Hermit Thrushes can also be defined by the introductory whistle note of their songs,” according to Williams College’s Heather Williams, an expert on song diversity who was not involved in the study. “The whistle note’s relative consistency across large geographical distances may be due to its role in long-distance communication of species or subspecies identity, while the remainder of the song could be under fewer constraints and its variability may carry more information about individual singers.”

Geographic variation in song structure in the Hermit Thrush (Catharus guttatus) is available at http://americanornithologypubs.org/doi/full/10.1642/AUK-16-222.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


Male Birds Adjust Courtship Behavior Based on Social Context

Wed, 05/17/2017 - 09:59

A male junco reacts to a caged female. Photo credit: J. Welklin

Male birds that have already paired up with a female aren’t above looking for a little action on the side. A new study from The Auk: Ornithological Advances explores how male juncos adjust their courtship behavior to their social landscape, finding that while both paired and unpaired males will try to get the attention of a new female on their turf, they go about it in different ways.

A male bird’s courtship behavior can be affected by factors like his size and hormone levels, but ornithologists are increasingly realizing that social context—whether or not the male already has a mate, and what other birds are around to witness his exploits—also plays a role. Dustin Reichard of Ohio Wesleyan University (formerly Indiana University) and his colleagues set out to tease apart the roles these different issues play in the courtship of Dark-eyed Juncos, comparing how unpaired males, paired males whose mates were present, and paired males whose mates were elsewhere behaved when presented with a new female.

They found that paired males approached females more rapidly, spent more time close to the females, were more active, and spent more time with their body feathers erect than unpaired males. Paired males also sang fewer long-range songs than their single counterparts, perhaps not wanting other birds to overhear, although the actual presence or absence of their mates didn’t affect their behavior.

Reichard had noticed variation in male juncos’ behavior during previous work to record their courtship songs, which led him to start developing hypotheses about what might underlie those differences. “Our results highlight the importance of considering both intrinsic and extrinsic factors when investigating the causes of variation in male courtship behavior,” says Reichard. “The focus of the field has generally been intrinsic factors, such as male condition or circulating hormone levels, but our results suggest a potential role for eavesdroppers and social context in addition to condition-dependent factors.”

Reichard and his colleagues conducted their experiments at Mountain Lake Biological Station in Virginia, placing caged female juncos in front of free-living males and observing the males’ reactions. After each trial, the researchers captured the male to record his size and weight and take a blood sample. “Often the male’s mate would respond aggressively to the caged female, diving at the cage while pausing occasionally to chase her mate away from the area. The males were usually shameless during this process and continued to approach while singing and displaying, but to our knowledge none of the pairs in our study divorced as a result of this brief infidelity,” says Reichard. “People called me a ‘junco homewrecker’ during these experiments, but there’s little evidence to support that accusation.”

In the future, Reichard hopes to explore the possibility that males use different strategies to target potential social mates—females they’ll raise chicks with—versus “extrapair” mates. According to Auburn University’s Geoffrey Hill, an expert on mate choice in birds who was not involved in the research, “This study shows the potential for extremely complex behavioral interactions in birds that were long thought to be bland monogamists.”

Condition- and context-dependent factors are related to courtship behavior of paired and unpaired males in a socially monogamous songbird is available at http://americanornithologypubs.org/doi/full/10.1642/AUK-16-214.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


AUTHOR BLOG: Tell me a story! A plea for more compelling conference presentations

Fri, 05/05/2017 - 10:53

Kathryn Langin

Linked paper: Tell me a story! A plea for more compelling conference presentations by K.M. Langin, The Condor: Ornithological Applications 119:2, May 2017.

At one point during last year’s North American Ornithological Conference, I found myself rushing down the hallways to catch a talk by a senior scientist whose research I have long admired. As I took my seat and he began speaking, I was immediately struck with the thought: “Darn, why did I make this mistake again?”

My mistake? Deciding to attend his talk and, in the process, failing to remember that I loathe his presentation style. The slides are always filled to the brim with volumes of text and a seemingly endless number of teeny-tiny figures. And despite going through them at a sprinter’s pace, he somehow fails to finish in the allotted fifteen minutes. It happens every time. The audience experience is akin to watching an action-packed commercial but, in the end, having only a vague sense of what was being advertised.

That incident and many others propelled me to write the Commentary “Tell me a story! A plea for more compelling conference presentations,” published this week in The Condor: Ornithological Applications. In it, I argue that scientists should spend less time trying to impress their audience with mountains of data and more time implementing principles of good storytelling. I know this probably elicits a negative reaction in some readers, but hear me out.

Stories aren’t a mode of communication restricted to fictional tales. They are the most effective way to package information so that others can process and remember it (which is really the whole point of communication, right?). It’s difficult to recall a series of random facts; it’s much easier to recall the details of an engaging story.

The nice thing about storytelling is that it is a natural fit for the scientific process. Dr. Randy Olson, author of the book Houston, We Have a Narrative: Why Science Needs Story, defines a story as “a series of events that happen along the way in the search for a solution to a problem.” Sound familiar? As scientists, we are always in hot pursuit of a solution to a problem, but unfortunately we don’t always present our research that way.

So how can we change that? For starters, it’s not sufficient to package information in a logical order with a beginning (introduction), middle (methods and results), and end (conclusions). That’s obviously helpful, but I argue in the paper that you need to go a step further and develop a compelling plot—something that compels your audience to follow along with your journey of discovery. That can be accomplished by clearly articulating a problem to be solved and spending time convincing the audience why they should care about the problem in the first place.

In his book, Dr. Olson outlines a strategy that I find particularly helpful. He suggests framing your story’s plot by proclaiming something that scientists know and something else that scientists know, but then pointing out a critical unsolved problem or point of debate that, therefore, highlights a need for your particular study. He calls this his “and, but, therefore” template, which contrasts with the template used by many scientists: one that strings along a series of facts with “and, and, and” statements. There’s no drama in “and, and, and” statements, but there is with the “and, but, therefore” framework.

A key advantage of Dr. Olson’s approach is that—by setting the stage in an informative and captivating manner—you can bring your entire audience with you on your journey, not just the people who already understand and appreciate your field and study system. And that should be the ultimate goal: to engage the widest fraction of your audience as possible.

The ornithological community is doing important and interesting science, but we don’t always do a great job communicating it, even amongst ourselves. In my paper, I argue for more storytelling, but I also discuss a greater range of strategies for giving effective presentations, including the benefits of visually-engaging slides. I don’t expect everyone to agree with me, but it is my hope that this opinion piece will generate thought and discussion about how to best communicate our science. We can’t afford to let important research be lost in a sea of ineffective communication.


Tracking Devices Reduce Warblers’ Chances of Returning from Migration

Wed, 05/03/2017 - 10:00

Geolocators like this one provide valuable data on bird migration but can also impact the birds that carry them. Photo credit: T. Boves

The tools ornithologists use to track the journeys of migrating birds provide invaluable insights that can help halt the declines of vulnerable species. However, a new study from The Condor: Ornithological Applications shows that these data come at a cost—in some cases, these tracking devices reduce the chances that the birds carrying them will ever make it back to their breeding grounds.

Geolocators are small devices attached to birds that record light levels over time, which can be used to determine location. They’re widely used to study migration patterns, but studies have suggested that some species may be negatively affected by carrying them. Douglas Raybuck of Arkansas State University and his colleagues monitored male Cerulean Warblers with and without geolocators to see how they fared, and they found that while geolocators had no effect on the birds’ nesting success in the same season following their capture, birds with geolocators were less likely to reappear on their territories after migration the next year—16% of geolocator-tagged birds returned from migration, versus 35% of the birds in the control group.

The data gained from geolocator studies are enormously useful for bird conservation, and on a global scale those benefits are likely to outweigh potential the costs. The results from this study suggest that the potential impacts of individual research projects need to be carefully evaluated, but we should remember that only a small number of birds are ever tagged relative to the total size of the population under study.

The researchers captured Cerulean Warblers in Pennsylvania, Missouri, and Arkansas by luring them into nets using call recordings and wooden decoys. Outfitting some with geolocators but others with only identifying color bands, they monitored the birds’ nests and then searched for them the following year to determine whether they’d returned. “Re-sighting males and identifying their unique color-band combinations as they moved about in the canopy was not always easy, but our dedicated and skilled field crew did a fantastic job of overcoming these obstacles, which were compounded by inclement weather and the rugged topography of the sites,” says Raybuck.

“New technologies such as geolocators and automated radiotracking arrays have led to a surge in new tagging studies of migratory songbirds,” according to York University’s Bridget Stutchbury, an expert on geolocators and the conservation biology of North America’s migratory songbirds. “Finding that tagged birds were far less likely to return the next year compared with un-tagged birds puts researchers in a serious dilemma, because despite the potential costs of tagging small birds, long-distance tracking is essential to find out which wintering and migratory stopover sites should be highest priority for conservation.”

Mixed effects of geolocators on reproduction and survival of Cerulean Warblers, a canopy-dwelling, long-distance migrant is available at http://americanornithologypubs.org/doi/full/10.1650/CONDOR-16-180.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


Review Highlights Challenges Faced by Birds in the Gulf of Mexico

Wed, 05/03/2017 - 09:57

More research is needed on the challenges faced by birds migrating through the Gulf of Mexico. Image credit: A. McBride

The Gulf of Mexico is hugely important to birds that migrate between North America and the Neotropics—almost all migrants have to go around it or across it. Coastal habitats around the Gulf of Mexico are critical for these migrating birds, but these habitats face more and more threats from human activity. A new Review in The Condor: Ornithological Applications brings together what we know—and don’t know—about the state of the region’s ecosystems and the birds that pass through them.

Understanding the population impacts of events during migration requires knowing which species are using what coastal habitats, how good those habitats are, where the birds are coming from, and where they’re going. Birds use a variety of coastal habitats, from vast tracts of hardwood forests to patches of vegetation embedded in agricultural or urban areas. The amount of food present in these areas, the intensity of competition for that food, and the danger from predators all shape how well a certain spot can meet a migrating bird’s needs. Threats to birds passing through the Gulf of Mexico include coastal habitat loss from forest clearing, wetland filling and dredging, and shoreline hardening; tall structures like cell phone towers and wind turbines; and, of course, climate change.

More data is needed in all of these subjects. Today the Gulf of Mexico Avian Monitoring Network is taking on the enormous task of coordinating monitoring across the region by integrating the efforts of multiple organizations and agencies. Doing this well will require close cooperation between the United States, Mexico, and Caribbean countries.

“Many migratory bird species are declining, including the species that breed in our backyards every summer, and we’re trying to understand if events that occur during migration might impact birds here on the breeding grounds. Our focus is the Gulf of Mexico region because it’s a bottleneck for migratory land birds—a place they have to move through every spring and fall,” says the Smithsonian Conservation Biology Institute’s Emily Cohen, the lead author of the Review. “Birds use these coastal habitats twice a year to eat and rest before and after their spectacular non-stop flight across the Gulf, which can take up to twenty hours! What’s going on during these migratory journeys is the final frontier for bird biology, and many new tools are making it possible to solve the mysteries of migration that previously limited our ability to develop conservation priorities.”

“This Review highlights the tremendous importance of the Gulf of Mexico to migratory birds, not only from an ecological and conservation perspective, but also as an opportunity to understand mechanisms that drive the evolution of migration across dozens of families,” according to Erik Johnson of Audubon Louisiana, an expert on bird conservation in the region. “As this paper makes clear, preserving this landscape is a tremendous responsibility shared across multiple countries, and our collective success has implications for how our descendants across North America will experience the amazing phenomenon of bird migration.”

How do en route events around the Gulf of Mexico influence migratory landbird populations? is available at http://americanornithologypubs.org/doi/full/10.1650/CONDOR-17-20.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


AUTHOR BLOG: Common Murre Parenting 101: How to Negotiate for an Easier Job

Wed, 04/26/2017 - 13:36

Researcher Linda Takahashi observes nesting murres. Photo credit: N. Oberlander

Linda Takahashi

Linked paper: Turn-taking ceremonies in a colonial seabird: Does behavioral variation signal individual condition? by L.S. Takahashi, A.E. Storey, S.I Wilhelm, and C.J. Walsh, The Auk: Ornithological Advances 134:3, July 2017.

When mates share parenting duties, conflict can arise over which one performs the hardest jobs. Common Murres are monogamous long-lived seabirds that raise only one chick each year. Extensive contributions from both parents are obligatory for successful chick fledging: Chicks are rarely abandoned, and murres are great parents. Throughout the three week chick-rearing period, one parent remains at the nest site, brooding and defending the chick, while the other is most often away from the colony foraging.  Murres have the highest wing loading of any flying bird, and so foraging far away from the colony, which is often necessary in years of reduced capelin availability, is energetically costly. Remaining in the colony with the chick is simply the easier job.

All things being equal between the murre parents, we’d expect that they would take turns and share the harder job of chick provisioning. For the most part, this is indeed what they do. One mate returns to the colony with a fish, feeds the chick, and the takes over brooding duties while the former brooder leaves. We called this a regular nest relief. However, some nest reliefs are irregular, such as when the returner comes back without a fish or the brooder doesn’t give up the chick, causing the returner to leave again to forage. We wondered if variation in nest reliefs was related to the relative physiological condition of the partners and whether changes in specific behaviours that occur during the nest relief ceremony were indicators of the partners “negotiating” with each other for the easier parental job.

Until our study, little focus had been given to the often-subtle behaviours shown by murres during nest relief (turn-taking) ceremonies. We looked at 16 pairs of Common Murres breeding in Witless Bay, Newfoundland, Canada, in 2009, a year with particularly low availability of capelin, the preferred forage fish. Pairs were identified by colour bands and nest location on the cliff. From dawn to dusk, we sat in a tiny observation blind and recorded murre behaviors with either a camcorder or an event logger. Specifically, an interaction began when a returning bird arrived at the nest, typically with a fish, and joined its chick-brooding partner, and it ended when one of the pair departed. We noted whether the parents traded roles and recorded their patterns of allopreening and bill-fencing. We also examined the relationships between murre condition—specifically, body mass and lipid metabolite levels (as measured by beta-hydroxybuterate)—and behavioural variation during turn-taking.

We found that irregular turn-taking ceremonies took longer than regular ones and had either delayed or non-synchronous allopreening. When a returning partner came to the nest without a fish, it began allopreening sooner than both the brooding partner and birds that returned with a fish. These “no fish” irregular nest reliefs took the longest of all, and brooders appeared to resist or delay leaving the colony. In cases where there was no exchange of duties, i.e., the brooder remained in the colony, rates of allopreening by the brooder were significantly lower than they were in all other types of turn-taking ceremony. Birds with higher overall chick-feeding rates brought fish on more visits than other birds, suggesting that that they were higher-quality individuals. Furthermore, brooding birds in relatively better condition departed the colony sooner after their mate fed the chick compared to those in relatively worse condition. We suggest that variation in allopreening allows mates to communicate with each other regarding their own condition, and, if that condition is poor, to negotiate for the easier parental duty, i.e., brooding.

Why would murres benefit from responding to signals about their mates’ condition? Since murres typically retain their mates for several years, parental investment theory predicts that it is in an individual’s best interest to preserve their mate’s current and future body condition as well as their own. Deterioration of a mate’s condition could lead to nest abandonment or even compromised survival. This paper shows that variation in ceremonies is one way to make information available to mates. Thus, behavioural variation during the ceremony can signal individual condition and be a means to negotiate parental roles.


Seabird Parents Compensate for Struggling Partners

Wed, 04/26/2017 - 13:36

A Common Murre at its nest. Photo credit: L. Takahashi

For species where both parents work together to raise their offspring, cooperation is key—it’s as true for birds as it is for us! A new study from The Auk: Ornithological Advances shows how pairs of Common Murres update each other on their condition so that when one partner needs a break, the other can pick up the slack.

Common Murre parents trade duties throughout the day—one stays at the nest while the other leaves to forage, hopefully coming back with a fish for the chick. Because brooding the chick requires much less energy than foraging, staying at the nest is preferable for a bird that’s in poor condition. Linda Takahashi, Anne Storey, and Carolyn Walsh of Newfoundland’s Memorial University, along with Sabina Wilhelm of the Canadian Wildlife Service, studied the “turn-taking ceremony” that parents perform when they switch places. They found that the time they spend preening each other provides a way for the two birds to exchange information about how they’re doing, so that if one is in poor shape the other can compensate.

The researchers observed 16 pairs of murres with chicks on an island off the coast of Newfoundland in summer 2009, recording their behavior when parents switched duties at the nest and capturing the birds to check their body condition. Their results show that these “nest relief” interactions take longer when one partner is especially low in body mass, suggesting that when brooders withhold preening and stall their departure, they’re letting their mates know that they need more time to rest; the returning mate can then compensate by going off to forage again rather than trading places immediately. Similarly, the brooding mate might let a struggling returner take over take over at the nest even if they haven’t brought back a fish.

“We had been doing murre field work for years in Witless Bay studying reproductive and parental behavior, and we became intrigued with the variation that we saw among pairs in their nest relief behaviors,” says Walsh. “Some nest reliefs were short and businesslike, while other nest reliefs seemed to involve a lot of interaction between the mates, and it took a long time for the mates to exchange brooding duty. When Linda Takahashi came to Memorial University as a master’s degree student, we decided that her project should focus on getting the details about this very interesting variation in murre nest relief behaviors.”

“The roles of avian pair members have been much studied in terms of energy investment and food delivery, but we are accustomed to thinking of these problems in terms of evolutionary tradeoffs. The ways in which contributions are actually negotiated within individual pairs has, until recently, been largely overlooked,” according to longtime seabird researcher Tony Gaston of Environment Canada. “Linda Takahashi’s paper addresses this deficiency, and this is a field which promises to open up additional avenues of research on within-pair communication.”

Turn-taking ceremonies in a colonial seabird: Does behavioral variation signal individual condition? is available at http://americanornithologypubs.org/doi/full/10.1642/AUK-17-26.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology that began in 1884 as the official publication of the American Ornithologists’ Union, which merged with the Cooper Ornithological Society in 2016 to become the American Ornithological Society. In 2009, The Auk was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.


Under-Studied Boreal Habitat Key for North America’s Ducks

Wed, 04/19/2017 - 10:10

Researchers used ducks harvested by hunters to learn new details about waterfowl migration. Photo credit: M. Carriere

Knowing where migrating birds came from and where they’re headed is essential for their conservation and management. For ducks, most of this information comes from long-term bird-banding programs, but this type of research has limits—despite all the birds harvested by hunters, only a small percentage of banded birds are ever recovered. A new study from The Condor: Ornithological Applications takes on the challenge of gaining information from unbanded birds by using stable isotope ratios, which reflect where birds were living while growing their feathers. These results reveal that the northern reaches of Canada may have underappreciated importance for North America’s waterfowl.

Canada’s Saskatchewan River Delta is North America’s largest inland delta and is a key stopover site for migrating ducks. To learn more about the origins of ducks using delta habitat, Christian Asante of the University of Saskatchewan, Keith Hobson of the University of Western Ontario, and their colleagues analyzed the isotopes in feather samples from 236 ducks from five species, all harvested by hunters in the region during migration in 2013 and 2014. Hydrogen and sulfur isotope ratios give scientists different information—hydrogen isotope ratios vary predictably with latitude, while sulfur isotope ratios reflect the type of food a bird eats and underlying geology—but together they indicated that as many as half the ducks using the delta during migration originated in the vast and nearly inaccessible areas of boreal forest and wetlands to the north.

The research required close collaboration with the area’s hunters. “Working on this project was a great experience,” says local community member Michela Carriere, who was hired to do the field work for the study. “I spent a few weeks collecting samples from the ducks and getting to know the hunters and the guides. Twice a day a load of ducks would come in and I would collect samples and label and package them, plucking feathers and extracting tissues. The hardest part was the labeling, which has to be done meticulously. I would spend hours each day collecting and organizing the samples.”

The results show that the boreal habitat’s contribution to North America’s waterfowl populations, though poorly documented, may be crucial. This region faces increasing threats from climate change and other factors, and isotopic monitoring offers a new means of tracking the effects on birds. “Our study is important for two reasons,” says Hobson. “First, it demonstrates clearly that the delta is a major fall refueling station for birds breeding in the north. Second, it shows once again how origins and regions of productivity can be determined using the simple isotope approach with feathers from hunter-killed birds. This major potential tool in waterfowl management has been largely overlooked in North America for too long.”

Tracing origins of waterfowl using the Saskatchewan River Delta: Incorporating stable isotope approaches in continent-wide waterfowl management and conservation is available at http://americanornithologypubs.org/doi/abs/10.1650/CONDOR-16-179.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists’ Union in 2016 to become the American Ornithological Society.


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