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.

Possible Oahu Populations Offer New Hope for Hawaiian Seabirds

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A juvenile Newell’s Shearwater. Photo credit: Lindsay Young.

The two seabird species unique to Hawaii, Newell’s Shearwaters and Hawaiian Petrels, are the focus of major conservation efforts—at risk from habitat degradation, invasive predators, and other threats, their populations plummeted 94% and 78% respectively between 1993 and 2013. However, a new study in The Condor: Ornithological Applications offers hope of previously undetected colonies of these birds on the island of Oahu, from which they were believed to have vanished by the late 1700s.

Shearwaters and petrels nest colonially in crevices, burrows, and under vegetation at mid to high elevations. They currently breed on other Hawaiian islands including Kauai and Maui, but were both believed to have extirpated from Oahu prior to European contact in 1778; biologists believed that occasional records from the island were birds thrown off-course at night by city lights.

Pacific Rim Conservation’s Lindsay Young and her colleagues used a spatial model based on elevation, forest cover, and illumination to identify potential suitable breeding habitat for both species on Oahu, then deployed automated acoustic recording units at 16 sites on the island to listen for the birds’ calls in 2016 and 2017, accessing remote mountain locations via helicopter. To their surprise, they detected petrels at one site and shearwaters at two sites.

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Automated acoustic recording units picked up the calls of endangered seabirds at remote locations on Oahu. Photo credit: Lindsay Young

“We were doing a statewide survey for these species for the U.S. Fish and Wildlife Service as part of recovery action planning, but Oahu was not initially included as one of the sites to survey, since evidence suggested they weren’t there,” says Young. “Since we’re Oahu-based, we thought we would at least put a few recording units out to see if there was anything. And we were surprised, to say the least, that we not only had calls detected, but detected both species across two years.”

These could be the last survivors of remnant breeding populations on Oahu, or they could be young birds from other islands that are searching for mates and breeding sites. “Either way, it gives us hope that we will be able to use social attraction—that is, using calls and decoys—to attract them nest on an island where they were once abundant,” says Young. Oahu birds could help boost connectivity between individual island populations and provide extra insurance in case any one island’s seabird population is decimated by an event such as a hurricane. As petrel and shearwater numbers continue to decline, protecting Hawaii’s remaining seabirds remains a major conservation priority in the region, and the possibility that they’re continuing to breed on Oahu provides new reason for optimism.

Evidence of Newell’s Shearwaters and Hawaiian Petrels on Oahu, Hawaii is available at https://academic.oup.com/condor/article/121/1/duy004/5298327.

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.

Homebody Tendencies Put Hawaiian Gallinules at Risk

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Hawaiian Gallinules’ limited dispersal may be putting them at risk. Photo credit: J. Underwood

The Hawaiian Islands are home to a range of unique, endangered bird species. Many waterbirds such as the Hawaiian Coot and Hawaiian Gallinule have been recovering in recent decades thanks to intensive wetland management, but past declines have left them with reduced genetic diversity. A new study from The Condor: Ornithological Applications looks at what the birds’ genes can tell us about their behavior today and finds that one species’ lack of wanderlust may be putting it at greater risk.

The U.S. Fish and Wildlife’s Jared Underwood and his colleagues trapped birds on Oahu and Kauai and took blood, tissue, and feather samples. Genetic analysis conducted at the U.S. Geological Survey by Sarah Sonsthagen and colleagues showed that Hawaiian Coots disperse regularly between islands, while Hawaiian Gallinules do not. The researchers believe that Hawaiian coot populations in some wetlands are reaching the maximum they can support, which is one factor causing them to leave in search of new territories. Historical evidence suggests that gallinules also moved around frequently prior to population declines, so either their behavior has changed, or, unlike the coots, they have yet to reach local carrying capacities.

“The Common Gallinule as a species is considered quite vagile—that is, it tends to move around a lot—so it was surprising to find a high level of genetic structure between two islands separated by only 175 kilometers,” says coauthor Jared Underwood. “Other Common Gallinule subspecies found in the Pacific frequently move between islands that are separated by greater distances.” Hawaiian Gallinules’ homebody tendencies put them at greater risk from severe one-off events like hurricanes, which could wipe out an entire island’s worth of birds. Their lack of gene flow also means that populations on individual islands need to be larger in order to be viable long-term.

Despite recent population gains, the researchers warn that rising seas, diseases, and introduced predators continue to threaten both species. “A key component of the resilience and persistence of species and populations is the retention of genetic diversity,” adds Underwood. “Information regarding the genetic structure for each species will allow managers to design different strategies and criteria for the species’ recovery.”

Interisland genetic structure of two endangered Hawaiian waterbirds: The Hawaiian Coot and Hawaiian Gallinule is available at http://americanornithologypubs.org/doi/full/10.1650/CONDOR-18-98.1.

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.