Male Birds Adjust Courtship Behavior Based on Social Context

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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

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

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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.

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Review Highlights Challenges Faced by Birds in the Gulf of Mexico

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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

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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

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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

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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.