PRESS RELEASE: Additions, Deletions, & Changes to the Official List of North American Birds

The latest supplement to the American Ornithological Society’s checklist of North and Middle American birds is being published in The Auk: Ornithological Advances, and it includes several major updates to the organization of the continent’s bird species. The official authority on the names and classification of the region’s birds, the checklist is consulted by birdwatchers and professional scientists alike and has been published since 1886.

Birdwatchers eager to build their “life lists” will be especially interested in the five species added to the checklist due to “splits,” where scientists have determined that bird populations once believed to be part of the same species are actually distinct; these newly-recognized species include the Choco Screech-Owl, Socorro Parakeet, and Stejneger’s Scoter. Eight species from Eurasia and South America have also been added to the list as a result of recent sightings in North America, and one species familiar to parrot fanciers, the Budgerigar, was removed from the list. Native to Australia, escaped pet “budgies” established a wild breeding population in central Florida in the 1950s. However, the population had been declining for decades, and as of 2014, Florida’s budgies have died out, possibly due to competition for nest sites from other non-native birds.

More than just a list that species are added to and deleted from, however, the checklist is also the authority on how North America’s bird species are sorted into genera and families based on their evolutionary relationships. This year, new genetic data led to the rearrangement of several of these groups. A genus of Neotropical tanagers called Tangara was split up, and a group of seabirds known as storm-petrels that were previously classified into two genera have now been lumped into a single genus called Hydrobates. AOS’s North American Classification Committee, the group of scientists responsible for the checklist, also made several tweaks to the names and classifications of hummingbird species, including taking the step of changing the official English name of one species that occurs in the southwestern U.S. and Mexico from “Blue-throated Hummingbird” to “Blue-throated Mountain-gem.”

“There are seven hummingbird species in the genus Lampornis, and all but two of them already had the common name ‘mountain-gem,’” explains committee chair Terry Chesser, USGS Research Zoologist at the Patuxent Wildlife Research Center. “Usually we don’t like to change the English names just to make them ‘better,’ because you could go through and make practically any bird name better if you wanted to, but in this case we thought it was worthwhile. We hope that calling all the birds in that genus by the name ‘mountain-gem’ will help birders understand a little bit more about the birds they’re looking at, both in terms of associating these seven species with each other and in recognizing them as distinct from species in other genera simply called ‘hummingbird.’”

Sixtieth Supplement to the American Ornithological Society’s Check-list of North American Birds is available at https://academic.oup.com/auk/article-lookup/doi/10.1093/auk/ukz042.

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.

Tracking Guam’s snake survivors

Henry Pollock

Linked paper: Pervasive impacts of invasive brown treesnakes drive low fledgling survival in endangered Micronesian Starlings (Aplonis opaca) on Guam by H.S. Pollock, J.A. Savidge, M. Kastner, T.F. Seibert, and T.M. Jones, The Condor: Ornithological Applications.

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A Micronesian Starling. Photo by Martin Kastner.

For bird aficionados, waking up on Guam can be a surreal experience. The soundscape is nearly devoid of birdsong other than the clucking of chickens and the occasional chirp of a Eurasian Tree Sparrow. Guam’s silent forests are the work of the brown treesnake, an invasive predator that was accidentally introduced to the island after World War II. Following its initial establishment on Guam, the brown treesnake population exploded, causing the extirpation of ten out of the island’s twelve native forest bird species within a few decades. However, a couple of species have managed to persist, and understanding how they’ve managed this feat in the face of such a formidable predator can inform future avian conservation strategies and snake suppression efforts on Guam.

Our research focused on the Micronesian Starling or Sali, a glossy black, gregarious bird that is a staple of forests throughout the Mariana Islands. On Guam, Sali declined precipitously following the introduction of the brown treesnake, but a small population has managed to persist in an urbanized landscape on Andersen Air Force Base in northern Guam. To understand why Sali have survived while so many other bird species have disappeared, we set out to study fledgling survival. The post-fledging period, when a bird has left its nest but is still dependent on its parents, is a period of great vulnerability, because young birds are often clumsy, sedentary, and less equipped to evade predators than adults.

To track fledglings through this crucial period, we attached small radio transmitters to Sali just before they left the nest and then came back each day to see whether our birds had survived the previous night and where they were spending their time. All of our birds fledged from nest boxes in an urban housing area, and tracking young birds through backyards on a military base was an interesting experience. We had regular run-ins with the military security forces, as well as also a lot of curious homeowners wondering what exactly we were doing decked out in field gear and holding large antennas! After a while, though, people got to know us, and many were truly interested in what we were doing and excited to know that they had a locally endangered bird species in their own neighborhood.

Our findings were staggering: only 25% of the fledglings survived, one of the lowest fledgling survival rates ever recorded for any bird species. The primary culprit was, of course, the brown treesnake, which caused approximately 60% of all mortality. However, cats were also an important source of mortality, responsible for around 20% of fledgling deaths. Beyond establishing these baseline numbers, however, we were also able to identify spatial patterns of predation risk and provide important management recommendations for future bird conservation on Guam.

We found that fledglings from nest boxes closer to the forest were more likely to be killed by brown treesnakes, indicating that locating nest boxes in core urban areas away from the forest perimeter would maximize fledgling survival. Furthermore, our data showed that brown treesnake predation actually extended weeks beyond the vulnerable post-fledging period, demonstrating again that these snakes are uniquely pernicious predators and that intensified snake control efforts are needed. We hope that our research provides impetus for further controlling the invasive brown treesnake and serves as a stepping stone for bringing birds back to Guam and enriching the island’s soundscape once again.

PRESS RELEASE: Study Reveals Key Locations for Declining Songbird

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Many of North America’s Prothonotary Warblers winter in the same small area of Colombia. Photo by Joan Eckhardt.

Many of North America’s migratory songbirds, which undertake awe-inspiring journeys twice a year, are declining at alarming rates. For conservation efforts to succeed, wildlife managers need to know where they go and what challenges they face during their annual migration to Latin America and back. For a new study published by The Condor: Ornithological Applications, researchers in six states assembled an unprecedented effort to track where Prothonotary Warblers that breed across the eastern U.S. go in winter—their “migratory connectivity”—and found that nearly the entire species depends on a relatively small area in Colombia threatened by deforestation and sociopolitical changes.

The Ohio State University’s Christopher Tonra and his colleagues coordinated the deployment of 149 geolocators, tiny devices that use the timing of dawn and dusk to estimate birds’ locations, on Prothonotary Warblers captured at sites across their breeding range. When the birds returned to their nesting sites the following year, the researchers were able to recover 34 devices that contained enough data for them to use. The geolocator data showed that regardless of where they bred, most of the warblers used the same two major Central American stopover sites during their migration and spent the winter in a relatively small area of northern Colombia. Additionally, many Prothonotary Warblers appeared to winter in inland areas, rather than in coastal mangrove habitat, which previous studies suggested they relied on most heavily.

These unexpected findings show that we may not understand the winter habitat needs of migratory songbirds as well as we thought. “The most surprising thing about the results was the overwhelming importance of Colombia to this species,” says Tonra. “We weren’t sure what to expect in terms of migratory connectivity, but we never expected that nearly every bird would use the same wintering region. This provided a clear conservation message and shows the power of geolocators in addressing gaps in our knowledge of migratory songbirds.” Colombia’s 50-year civil war accelerated deforestation in the region of the country where the warblers are concentrated, but the good news is that the convergence of birds in this single area means that conservation efforts targeted here could benefit breeding populations across North America.

Collecting data on birds across such a broad geographic area required close collaboration among the study’s thirteen coauthors. “This was very much a team effort, but it really started with Erik Johnson at Audubon Louisiana and Jared Wolfe with the Louisiana Bird Observatory,” says Tonra. “Erik founded and leads our Prothonotary Warbler Working Group, and he initiated the idea of deploying tags across their range. This was an extremely rewarding example of what you can accomplish through collaboration across the range of a species of concern. Everyone put in an enormous effort to gather data in their region, as well as contributing to the preparation of the paper.”

Concentration of a widespread breeding population in few critically important nonbreeding areas: Migratory connectivity in Prothonotary Warbler is available at https://academic.oup.com/condor/article-lookup/doi/10.1093/condor/duz019.

About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology, published by the American Ornithological Society. For the past two years, The Condor has had the number one impact factor among 27 ornithology journals.

Announcing the New Wesley Lanyon Award

Dad recording avian vocalizations Fall 1968 (DD126)
Wesley “Bud” Lanyon.

The AOS Council is pleased to announce a new annual publication prize, the Wesley Lanyon Award. This new award will recognize the early-career ornithologist who authors the best synthesis/review paper on avian science to be published as an open-access article in either AOS journal (The Auk or The Condor). Members of AOS who are within or up to the end of their third year post-PhD are invited to compete for the award. Reviews encompassing basic and/or applied research subdisciplines in ornithology are eligible.

The Wesley Lanyon Award will provide a $1,000 honorarium to the winner, as well as a $1,000 travel stipend and gratis registration to attend the AOS annual conference, where the winner will organize a symposium on their winning review topic. Wesley “Bud” Lanyon served as the 37th President of the American Ornithologists’ Union. Bud was a steadfast and committed leader in the field of ornithology and was a respected mentor of many generations of scientists. He was particularly keen to support researchers in the midst of writing their dissertations and those who had recently completed their PhDs. Because they possess a thorough understanding of the current literature, he recognized, they are poised to provide novel insights into classic areas of ornithology and to elucidate emerging fields of study.  

The winner of the inaugural award will be announced in the spring of 2020, and the award will be presented at our 2020 annual meeting in Puerto Rico. The first step in competing for the award will be to submit an abstract for the proposed review by August 30, 2019; the journal Editors-in-Chief and the four Deputy Editors will review the abstracts and invite up to six competitors to submit their manuscripts to the appropriate journal.

“This award competition will highlight the excellent research of early career ornithologists, produce timely and valuable scholarship for our readers, and increase the scientific impact of AOS journals,” says Scott Sillett, Editor-in-Chief of The Auk. AOS editors are looking forward to reviewing your submissions, so get writing!

Studying “song neighborhoods” within sabrewing leks

Juan Francisco Ornelas

Linked paper: Male relatedness, lekking behavior patterns, and the potential for kin selection in a Neotropical hummingbird by C. González and J.F. Ornelas, The Auk: Ornithological Advances.

A Wedge-tailed Sabrewing. Photo by Clementina González.

About 25 years ago, I started a research position at the Instituto de Ecología AC in Veracruz, Mexico. During my first explorations of the cloud forest there, I heard the marvelous sound that eventually became a key part of my work and that of my assistant Clementina González. After spending my graduate school years at the University of Arizona and learning the sounds of the Sonoran Desert, I decided to tape record the unfamiliar sound, a decision that resulted in a great journey.

When I was field hunting for the sound, holding my old tape recorder, I soon heard swooshing noises and the mystery sound coming from somewhere in the bushes and thickets of the understory, but at first I could not see what was making it. Suddenly, I spotted it: a Wedge-tailed Sabrewing! These birds are among the most common hummingbirds in the area, or at least the most belligerent. Males are polygamous and (like all male hummingbirds) do not participate in raising the young, but this species forms leks, which are areas where males sing to show off and females choose mates.

Years later, Clementina started recording songs from different groups, and she realized that they sounded different. Once we were familiar with the behavior of Wedge-tailed Sabrewings, we documented the structure and variation of their songs within and between singing groups in central Veracruz. What we found was very exciting. Locally known as fandanguero (because it sings all day long like local folks at the fandangos), the Wedge-tailed Sabrewing has a song that is complex and variable, composed of more than 20 different syllable types per individual. We found a total of 239 different syllable types among the eight singing groups we studied.

This became the basis of Clementina’s doctoral thesis. She started to record songs from leks across their geographic distribution and showed that their song varies throughout eastern Mexico, where populations of three subspecies (curvipennis, excellens, and pampa) are disconnected. When she looked at their DNA, lek members clustered into the three subspecies and could also be distinguished by their songs. We wondered, what caused the genetic and behavioral differences? Genetic drift (the accumulation of random mutations in a population) could partially explain their genetic and behavioral differences, because the members of populations of one subspecies don’t mate with the others. But the genetic drift alone is not enough to fully explain the observed song variation within and among leks of each of the subspecies. Some sort of selection might be occurring.

We wanted to explore more deeply what was happening inside the leks. Clementina realized that males within a lek also sang differently and that males with different songs were clustered spatially, with an introductory syllable in their songs as the signature of a song neighborhood. It is not clear at this point in our research how and why these unique and variable complex acoustic signals have evolved in some but not all lekking species of hummingbirds, but we’re working on figuring it out.

For our newest study, published in The Auk: Ornithological Advances, we asked whether lek formation and the existence of song neighborhoods within leks are due to kin selection. In this system, kin selection would occur when a member of a song neighborhood engages in self-sacrificial behavior that benefits the genetic fitness of its relatives in the neighborhood. To address this, we genotyped males in leks located across the distribution of Wedge-tailed Sabrewings as well as in a focal lek composed of song neighborhoods and estimated their relatedness — not an easy task! Most males within leks were unrelated, and song neighborhoods were not composed of related individuals. This means that kin selection is not acting on the formation of leks or song neighborhoods in this species, suggesting that membership in song neighborhoods is achieved by learning the song of the neighborhood, regardless of kinship.

Clementina González website

Juan Francisco Ornelas website