Rainy weather predicts bird distribution—but climate change could disrupt it

AUK-17-209 EAKI M MacPherson

Precipitation is the best predictor of Eastern Kingbirds’ winter distribution. Image credit: M. MacPherson

Understanding what environmental cues birds use to time their annual migrations and decide where to settle is crucial for predicting how they’ll be affected by a shifting climate. A new study from The Auk: Ornithological Advances shows that for two species of flycatcher, one of the key factors is rain—the more precipitation an area receives, the more likely the birds are to be there during the non-breeding season.

Tulane University’s Maggie MacPherson and her colleagues combined field techniques with species distribution models to investigate which environmental factors drove the migrations of Eastern Kingbirds and Fork-tailed Flycatchers. Using geolocators, devices that record a bird’s daily location based on day length, they could track where individuals of each species went. The two species share similar behavior and habitat requirements, but differ in their range and migration strategies, and these strategies were compared to determine the influence of temperature, precipitation, and primary productivity (the amount of “green” vegetation). Precipitation turned out to be one of the most important predictors of their distribution, particularly in the non-breeding season.

MacPherson comments, “Although we understand how climate change is expected to affect regional temperature regimes, changes in patterns of seasonal precipitation remains unclear. As the locations of both species were positively correlated with the highest rainfall across the landscape during their non-breeding seasons, our research emphasizes the need for a better understanding of how flexible they may be in adjusting locations under new rainfall regimes. More research is needed to better understand how migratory birds relying on current rainfall regimes could benefit from climate-conscious conservation planning.”

“In the face of climate change, having seasonal species distribution models like these is powerful for helping understand the biology of the species, and also for predicting how a population might change in size and geography in the future, or a species’ flexibility to adjust its migratory timing,” adds Mississippi State University’s Auriel Fournier, an expert on species distribution models who was not involved in the study. “All of those predictions are vital for conservation planning and decision making. The use of two related species with different life history traits is also exciting, as it makes the results more broadly applicable.”

Follow the rain? Environmental drivers of Tyrannus flycatcher migration across the New World is available at http://www.bioone.org/doi/full/10.1642/AUK-17-209.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The Auk commenced publication in 1884, and in 2009 was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Piping Plovers want people to get off their lawn

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Banded Piping Plover in non-breeding plumage (Photo Credit: Kelley Luikey)

A new study in The Condor: Ornithological Applications presents negative associations between anthropogenic disturbance (human recreational use of beaches, coastal modifications) and Piping Plovers on their non-breeding grounds. Shorebirds are one of the most threatened bird families in the world. Numerous studies have shown the negative impacts of humans on these birds, whether it be large-scale (e.g., habitat loss, climate change) or small-scale (e.g., ATV use, running with pets, flying kites). This research indicates that there are direct consequences of disturbance. Most Piping Plover research has focused on the breeding season in an attempt to directly influence population numbers, however this study argues that efforts are required throughout the year in all locations to assist Piping Plover conservation.

Virginia Polytechnic Institute and State University’s Dan Gibson and colleagues monitored Piping Plovers year-round to determine the health and behavior of individuals. Body condition, survival, and site fidelity were of most interest. Plovers in disturbed areas proved to be significantly lighter in mass, due to the birds not procuring enough food. Given poorer body condition, it should be no surprise that birds in these disturbed areas also had lower survival rates. Piping plovers have strong site fidelity on the breeding grounds and this study supports that fidelity continues on the non-breeding grounds. While physically capable of changing location, it was not common for individuals to do so even if there was a high level of disturbance. The lack of movement by disturbed individuals suggests that aspects of the species’ life history (i.e. fidelity) constrained individuals to make seemingly adaptive habitat-use decisions. Some of the strategies used on the breeding grounds (reduced human recreation, roped-off areas, no dogs on beaches) may be beneficial to also do on the non-breeding grounds to ensure year-round conservation and oversight on this threatened shorebird species.

Lead author Dan Gibson comments, “We have a lot of of opportunity to engage with the public in what exactly our research is about. We often try to stress that the impact an individual recreationist has on a shorebird is practically non-existent. However, if every person who uses a beach in a given day influences how these shorebirds feed or rest, those minute impacts can begin to add up over the course of a season that can manifest itself as reductions in individual body condition and ultimately their ability to withstand bad weather conditions or successfully migrate and find a mate. We try to stress that small changes in how we use a beach (e.g., keep dogs on leash, avoid running through groups of birds) can really add up to substantial improvements in the overall quality of coastal habitat for shorebirds.”

“This study availed itself of a unique resource that range-wide banding efforts have provided for the study of the demographics of the endangered piping plover,” adds College of Environmental Science and Forestry Associate Professor Jonathan Cohen, a shorebird expert who was not involved with the research, “and successfully attempted the difficult task of teasing out the sometimes subtle effect of disturbance in nonbreeding areas on annual vital rates.  The finding that this endangered species may not readily abandon habitat that is detrimental for fitness was surprising, and warrants immediate attention from the conservation community.”

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Impacts of anthropogenic disturbance on a non-breeding shorebird’s body condition, survival, and site fidelity is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-148.1.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The journal began in 1899, and in 2016 The Condor had the number one impact factor among 24 ornithology journals.

Crows are always the bullies when it comes to fighting with ravens

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Three Crows (left) versus one Raven (right) (Photo credit: PhillipKrzeminski)

A study from The Auk: Ornithological Advances presents citizen science data which supports that American Crows and Northwestern Crows almost exclusively (97% of the time) instigate any aggressive interactions with Common Ravens no matter where in North America. The data showed that aggression by crows was most frequent during the breeding season, most likely due to nest predation by ravens. This study not only gives insight into interspecies dynamics, but also how citizen science data can aid behavioral studies at large geographic scales.

Cornell University’s Ben Freeman and colleagues used more than 2,000 publicly collected and submitted observations from across North America via eBird to analyze the interspecific aggression between crows (American and Northwestern) and Common Ravens. From these records, it was determined that crows were the predominant aggressor. Crows primarily attacked in small groups rather than one-on-one confrontations with ravens. The breeding season was when most of the attack observations were made, suggesting that nest predation by ravens influences this behavior. Aggression during the winter is potentially explained by crows preemptively deterring nest predation and defending resources needed for nesting later in the year. This study was made possible by citizen scientists who were not even asked to submit such observations. Given this was passively collected data that aided in a behavioral study on a large geographic area, it could act as a model for other research and potential studies conducted.

Lead author Ben Freeman comments, “There are two take-home messages. First, we show that bigger birds do not always dominate smaller birds in aggressive interactions, and that social behavior may allow smaller birds to chase off larger birds. Second, this is a case example of the power of citizen science. It would be next to impossible for even the most dedicated researcher to gather this data across North America. But because there are thousands of people with expertise in bird identification and an interest in bird behavior, we can use data from eBird to study behavioral interactions on a continental scale.”

“Given that aggression between crows and ravens can be quite conspicuous, birders and the general public are often the observers of such interactions,” adds Kaeli Swift of the University of Washington, who was not involved with the research, “yet despite the ease and frequency of witnessing these events, there was little scientific information for curious minds to turn to for explanation. It’s quite rewarding then, that the citizen scientists that may have wished for this information are the very people whose observations made this publication possible.

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Why do crows attack ravens? The role of predation threat, resource competition and social behavior is available at http://www.bioone.org/doi/full/10.1650/AUK-18-36.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The Auk commenced publication in 1884, and in 2009 was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

To help save Northern Spotted Owls, we need to prevent kissing cousins

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Spotted Owl (Photo Credit: Alan Dyck)

The Auk: Ornithological Advances presents a study on a Northern Spotted Owl pedigree, consisting of almost 14,200 individuals over 30 years, which determined inbreeding varies across the species’ range. Selection against inbreeding based on decreased future reproduction, fewer offspring, and overall survival of individuals was also supported. These results indicate that Spotted Owl conservation efforts need to address owl breeding more. Another implication of this work is the need to increase genetic diversity to prevent further population decline.

Mark Miller of the United States Geological Survey (USGS) Forest and Rangeland Ecosystem Science Center, and colleagues employed field and statistical methods to create a family tree for Northern Spotted Owls living in California, Oregon, and Washington. From this, the researchers determined how often inbreeding occurs in the wild for these birds. Fourteen types of matings among relatives were determined with most inbreeding relationships being between half or full siblings. It was discovered that inbreeding is most common in the Washington Cascades (~15% of individuals are inbred), while the lowest inbred population was Northern California (~2.7% of individuals). The explanation for this geographic variation may be the rate at which specific populations are declining and experiencing bottlenecks. Conservation efforts are vital today given that Northern Spotted Owls are already facing habitat loss and competition with a similar species, the Barred Owl. This study showed that both the physical consequences of inbreeding (physical deformities, reduced ability to adapt) and the reproductive fitness of individual birds (infertility, future reproduction, decreased survival) need to be taken into account since both influence this species’ success. Translocating birds among populations to help increase the genetic diversity may be a potential management strategy.

Lead author Mark Miller comments, “Long-term studies, similar to the one described in this paper, are key to understanding how common or rare inbreeding is in natural populations. An understanding of the extent of inbreeding can help resource managers better identify appropriate measures to conserve threatened and endangered species.”

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Variation in inbreeding rates across the range of Northern Spotted Owls (Strix occidentalis caurina): Insights from over 30 years of monitoring data is available at http://www.bioone.org/doi/full/10.1650/AUK-18-1.1.

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The Auk commenced publication in 1884, and in 2009 was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

It’s go time for Hawaiian bird conservation, and luckily there’s a playbook

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‘I’iwi (Photo credit: Lucas Behnke)

A new study in The Condor: Ornithological Applications presents some of the best guidance to date on the priorities and actions that can be taken to help Hawaii’s endemic birds. Hawaii’s ecosystems, including its native bird populations, are struggling. Of the 21 species of forest birds left on the islands, almost two thirds (12 species) of are endangered or threatened. The current conservation status of the wildlife and vegetation on the island is almost entirely attributable to humans. The actions needed to stabilize or reverse these trends need stronger support and coordination, however funding and resources are limited. This new paper lays out a plan to better guide and empower conservation efforts for Hawaiian birds.

Eben Paxton of USGS Pacific Island Ecosystems Research Center and colleagues synthesized the key points that came out of a collaboration of more than 60 stakeholders in Hawaiian bird conservation. The focus is on actionable research and management approaches that can be employed today. Habitat loss, invasive plants, non-native predators, and introduced diseases were identified as the largest threats to Hawaiian birds. Climate change is projected to exacerbate all threats. Given limited resources, the stakeholders decided on eight main priorities as well as several actions specific to the island of Kauai. In addition to helping Hawaii and its birds directly, the goal of this collaborative report is to make Hawaii a model for other areas of the world, especially islands, that are in need of strong conservation efforts.

Lead author, Eben Paxton comments, “Our challenge in Hawaii is how do we conserve forest birds from multiple threats with just a fraction of the resources needed to fully address all the threats. Our solution was to bring researchers and managers together to share ideas, and as a community, identify priority research and management needs necessary to save these unique species. We believe these priorities will help focus resources where most needed and bring together different organizations to work together for the maximum benefit of the birds.”

“New Technology is being proposed to help stem the tide of extinctions in Hawaiian native birds. Eben Paxton and his co-authors recognize that all the native birds in Hawaii are Conservation Reliant Species and propose utilizing new technologies to assist with the preservation of this unique island avifauna,” adds Charles van Riper III, a ST Research Ecologist and Professor Emeritus, USGS and SNRE, University of Arizona. “This very complete paper also recommends enhancing Citizen Science and captive breeding in the Islands, along with continued monitoring and translocations to unoccupied habitat. The immediate target for this plan are the birds on Kauai – the authors feel that the native avifauna on this island is rapidly approaching extinction, and time will tell how successful this proposed plan is in implementing conservation actions in time to save these unique birds.”

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Research and management priorities for Hawai’i forest birds is available at http://www.bioone.org/doi/full/10.1650/CONDOR-18-25.1.
Research contact: Eben Paxton, epaxton@usgs.gov

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The journal began in 1899, and in 2016 The Condor had the number one impact factor among 24 ornithology journals.

 

When You’re a Sitting Duck, You Learn to Adapt

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Common Loon on nest dealing with black flies (Photo credit: Linda Grenzer)

When sitting on a nest to incubate eggs, a bird is physically stuck and most vulnerable to attacks of any kind, so coping without stress and other significant costs is important. For Common Loons, black flies are a common blood-feeding pest and can cause nest abandonment and decreased fledging rates. This has impacts on not only individual pair success, but on population dynamics as well. A new study from The Auk: Ornithological Advances presents some of the best data to date supporting hypotheses about the effects that black flies have on Common Loon nesting behavior and success.

Chapman University’s Walter Piper and colleagues monitored Common Loon nests for 25 years in northern Wisconsin, USA. They marked individuals to track each bird’s behavior, nesting success, and interaction with black flies. More than 2,050 nests were included in the study to apply the impacts of black flies on loons’ population level. If the black fly concentration around an individual bird was high or there was a particularly intense fly outbreak year, loon incubation time decreased and nest abandonment increased. It was discovered that nest abandonment could be predicted using lake size, female age, and wind. The team found that the smaller the lake, the older the female, and the greater the distance across water that wind has to travel to reach the nest the more likely the nest will be abandoned. The cost associated with severe black fly outbreaks appears to be high enough that a nest can be abandoned and a second attempt made following the peak of the outbreak. The second nest is likely to be in the original location unless a predator destroyed the nest. In that case, the pair is more likely to choose a new and hopefully safer nest site.

Lead author Walter Piper comments, “Black flies, which we think of as a nuisance and no more, actually impact population reproductive success. This was a matter of studying an animal for 25 years and almost ignoring one aspect of their biology — until you finally look straight at that aspect of biology and realize it’s crucially important! Loons get slammed by black flies, but they make a very good response by reusing the nest sites where the flies hounded them, instead of abandoning those sites altogether — as they do when raccoons get their eggs. This makes sense, because the raccoons are their main enemies (that is, egg predation is a more severe problem then black flies), and a safe nesting site from raccoons is a vital resource.”

“This study is one of the first that examines the negative influence of black flies on a population of birds rather than on individuals alone. Perhaps more importantly, by studying a marked population of loons for almost a quarter century, it is possible to determine the stochastic influence of black fly outbreaks on the population as well as understand the nuances of how these mechanisms might work,” adds Jeb Barzen, an ecologist with Private Lands Conservation, who was not involved with this study. “Black flies severely reduce reproductive effort of loons periodically but not every year, a finding that is important to understanding the population dynamics of this iconic species. The more subtle examination of individual response to black flies provides insight into differences in how males and females, as well as individuals in different habitats and individuals of different ages, respond to black fly infestations. Collectively these results inform ecologists and managers alike in issues relevant to the conservation of loon populations and other long-lived, territorial bird species.”

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Common Loons respond adaptively to a parasite that impacts nesting success is available at http://www.bioone.org/doi/full/10.1642/AUK-17-239.1
Researcher contact: Walter Piper, wpiper@chapman.edu

About the journal: The Auk: Ornithological Advances is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The Auk commenced publication in 1884, and in 2009 was honored as one of the 100 most influential journals of biology and medicine over the past 100 years.

Original habitat is best, but restoration still makes a big difference

CONDOR-17-189_YBCHnest_Melissa C. Roach

Yellow-breasted Chat nest with chicks. (Photo Credit: Melissa C. Roach)

A new study in The Condor: Ornithological Applications presents some of the best evidence to date that restoration efforts in Missouri’s Ozark Highlands make a difference for nesting songbirds that breed there. The reduction of Missouri pine savannah and woodland areas has caused birds that rely on these habitats to decline. Current efforts to bring these habitats back are under way and include prescribed fire and thinning tree stands. Recent studies support that these efforts are making a positive impact on the ecosystem and increasing the survival of bird species that breed there.

Melissa Roach of the University of Missouri and colleagues investigated the relationship between daily nest survival and habitat and restoration efforts. Her team studied six species comprising two groups: shrub-nesters and canopy-nesters. Eastern Towhee, Prairie Warbler, and Yellow-breasted Chat were representative of shrub-nesting species, while canopy-nesting species included Eastern Wood-Pewee, Pine Warbler, and Summer Tanager. After monitoring nests for two years, researchers found that predation was the number one cause of nest failure. Current restoration efforts (fire and tree thinning) directly influenced the ground layer of vegetation. This changed the cover available to both hunting predators and hiding prey, changing the predator–prey dynamics. Thus, restoration efforts and maintaining a varied landscape for wildlife is important for the success of these songbirds.

Lead author Melissa Roach comments, “We found strong results that should help guide land managers when it comes to important management decisions regarding the restoration and maintenance of rare or sensitive habitats. Not only were we able to show that these species are responding positively to pine woodland restoration, we provided baseline nest survival data for some understudied species. We also hope that this study increases the public’s awareness and appreciation of just how important prescribed fire and tree thinning can be for wildlife.”

“As the Coordinator of the Central Hardwoods Joint Venture, the regional partnership guiding bird conservation across the Ozarks and Interior Low Plateaus ecoregions, I find it gratifying to see research showing that the restoration of fire-dependent natural communities like shortleaf pine woodlands has such a positive effect on populations of bird species of conservation concern,” adds Jane Fitzgerald, of the American Bird Conservancy and Central Hardwoods Joint Venture Coordinator. “While we have, in the past, focused much of our planning on increasing carrying capacity by increasing the amount of high-quality habitat available to a species, we are learning that it’s just as important to evaluate how management impacts the vital rates that drive population growth. I hope we see more and more research that provides that kind of ‘big picture’.”

 

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Songbird nest success is positively related to restoration of pine–oak savanna and woodland in the Ozark Highlands, Missouri, USA is available at http://www.bioone.org/doi/full/10.1650/CONDOR-17-189.1.
Research contact: Melissa C. Roach, roach.mc1@gmail.com

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology published by the American Ornithological Society. The journal began in 1899 and in 2016 The Condor had the number one impact factor among 24 ornithology journals.