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.

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.

PRESS RELEASE: UV Lights on Power Lines May Help Save Sandhill Cranes

Illuminating power lines with UV lights could reduce collisions by Sandhill Cranes. Photo by James Dwyer, EDM International.

Crane species are declining around the world, and lethal collisions with power lines are an ongoing threat to many crane populations. Current techniques for marking power lines and making them more visible to cranes aren’t always effective, but new research published in The Condor: Ornithological Applications shows that adding UV lights—to which many birds are sensitive—can cut crane collisions with power lines by 98%.

EDM International’s James Dwyer and his colleagues created what they dubbed the Avian Collision Avoidance System, or ACAS, by mounting UV lights on power lines’ supporting structures and shining them on the lines at night. They tested its effectiveness in 2018 at Nebraska’s Iain Nicolson Audubon Center, where a power line crosses the Central Platte River in key habitat for migrating Sandhill Cranes. Randomly assigning the ACAS to be on or off each night, they observed the behavior of cranes flying along the river at dusk and during the night. They documented 98% fewer collisions and 82% fewer dangerous flights when the ACAS was on and showed that cranes reacted sooner and with more control to avoid hitting the power lines.

“This project came about as a result of years of studying avian collisions with power lines throughout North America. My studies included collisions involving numerous species and families of birds, even on lines modified to industry standards to mitigate avian collisions, and I thought perhaps there could be a more effective approach,” says Dwyer. “Even so, I did not imagine that the ACAS would have the effect that it did—a 98% reduction in collisions! I thought it would have some effect, but I didn’t dare think the ACAS would pretty much solve the Sandhill Crane collision problem at our study site on our first try.”

The Avian Collision Avoidance System at night. Photo by James Dwyer, EDM International.

Conventional line markers were already in place on the power lines crossing the Central Platte River, and Dwyer and his colleagues speculate that the ACAS illuminated them and made them easier for cranes to see. “We don’t know how effective the ACAS will be on wires without line markers, so we’re testing that now,” says Dwyer.

“I hope to see the ACAS applied to and studied on other power lines and on communication towers to identify whether it is as effective with other species, habitats, and wire configurations,” he continues. “From there, if the ACAS proves broadly effective, I hope to see it made easily available to the global electric industry. I also very much hope to see collision studies expanded. Because large carcasses like those of cranes and waterbirds are more easily noticed than smaller species like sparrows and warblers, collision studies have mostly focused on those larger species, and I fear that we may not understand the true distribution of species and habitats involved in the global avian collision problem.”

Near-ultraviolet light reduced Sandhill Crane collisions with a power line by 98% is available at https://academic.oup.com/condor/article-lookup/doi/10.1093/condor/duz008.

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.

PRESS RELEASE: Do Songbirds Pay a Price for Winter Wandering?

The greater the magnitude of nuthatch’s winter irruption, the lower the next summer’s breeding population.

In years when winter conditions are especially harsh, birds that depend on conifer seeds for food are sometimes forced to leave their homes in northern forests and wander far from their normal ranges to find enough to eat. A new study published in The Auk: Ornithological Advances uses citizen science data to show for the first time that these winter movements—called “irruptions”—lead to a decline in birds’ population density in their breeding range the following summer, suggesting that irrupting birds succumb to the difficulties of avoiding predators and finding food in unfamiliar landscapes.

Many birdwatchers love irruptions, because they can temporarily bring seldom-seen boreal birds south in large numbers. However, we know very little about how these journeys into unfamiliar territory actually affect bird populations. Red-breasted Nuthatches are a useful species in which to study this, because they return to the same core breeding areas even after winters with massive irruptions, making it possible to track how their breeding populations are doing from one year to the next.

Environment Canada’s Erica Dunn checked more than fifty years of records from Ontario’s Long Point Bird Observatory (LPBO) against citizen science data from Project FeederWatch, the Christmas Bird Count, and eBird to confirm that fall irruptions at Long Point are a good indicator of what’s going on with nuthatches across North America in any given year. Then, she used Breeding Bird Survey data to see how nuthatches fared in summers following major irruptions and found that breeding population density tended to dip noticeably after a winter where nuthatches had wandered more widely than usual.

This is the first study to demonstrate a correlation between the magnitude of birds’ winter irruption and their population density during the following breeding season. While these large-scale winter movements may be a necessity for birds in years where food is scarce, the rigors of travel, exposure to predators, and need to find food in unfamiliar places might take a toll.

“This paper actually had its genesis over 30 years ago, when I was running LPBO’s Ontario Bird Feeder Survey and noticed that feeder watchers were reporting more nuthatches in winters following large fall irruptions at Long Point. When the biggest irruption ever at LPBO occurred in 2012, I was inspired to use their fifty-plus years of data to investigate that old observation in more detail,” says Dunn. “It was truly a project without a particular goal or hypothesis—I simply had a great dataset and wanted to see what I could learn from it. Citizen science data are great for this kind of exploration, because the datasets are so large and are freely available to anyone who wants to work with them.”

Dynamics and population consequences of irruption in the Red-breasted Nuthatch (Sitta canadensis) will be available April 15, 2019, at https://academic.oup.com/auk/article-lookup/doi/10.1093/auk/ukz008.

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.

Road Proximity May Boost Songbird Nest Success in Tropics

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A juvenile White-rumped Shama with identifying leg bands. Photo credit: Rongrong Angkaew

In the world’s temperate regions, proximity to roads usually reduces the reproductive success of birds, thanks to predators that gravitate toward habitat edges. However, the factors affecting bird nest success are much less studied in the tropics—so does this pattern hold true? New research published in The Condor: Ornithological Applications shows that interactions between roads, nesting birds, and their predators may unfold differently in Southeast Asia.

Rongrong Angkaew of King Mongkut’s University of Technology Thonburi and her colleagues placed 100 next boxes for the cavity-nesting White-rumped Shama in forest interior and 100 near a road at an environmental research station in northeast Thailand. Monitoring nests and radio-tracking 25 fledglings from each site for seven weeks, they found that nest success was 12% higher and post-fledging survival 24% higher at the edge versus the interior—the opposite of the pattern commonly observed in temperate regions.

“There were some special challenges involved in carrying out the field work,” says Angkaew. “When we started setting up the nest boxes in the field, we found a lot of tracks and other signs of poachers and illegal hunting, so we had to avoid some parts of the forest edge in order to reduce human disturbance to our nest boxes, which could have affected nestling and fledgling survival rates.”

Predators caused 94% of nest failures and 100% of fledgling mortality, and locally important predators of small birds, such as green cat snakes, northern pig-tailed macaques, and raptors, appear to prefer interior forest habitat. Fledglings also preferred to spend time in dense understory habitat, which provides cover from predators and was more available near roads.

Overall, the study’s results suggest that the effects of roads on birds’ reproductive success depend on local predator ecology—the same rules don’t necessarily apply in different biomes. Angkaew and her coauthors hope that more studies like theirs will help identify key nest predators and assess their foraging behaviors in multiple landscapes, in order to determine the best ways to conserve vulnerable bird species in areas affected by human development.

Nesting near road edges improves nest success and post-fledging survival of White-rumped Shamas (Copsychus malabaricus) in northeastern Thailand is available at https://academic.oup.com/condor/article/121/1/duy013/5303795.

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.