Rare hybrid bird discovered in Deep Lock Quarry Metro Park

6/27/2019 - West Side Leader

By Stephanie Walton

SUMMIT COUNTY — The conservation staff at Summit Metro Parks (SMP) is always up to something new and exciting. From releasing rare turtles back into the wild, to raising honeybees, to studying the behavior of bats and coyotes, their work routinely uncovers new information that informs ecosystem management and species protection. But one recent discovery stands out from the rest.

While studying migrant bird species in Deep Lock Quarry Metro Park and the Cuyahoga Valley, former SMP biologist Ryan Trimbath found the key to unlocking a decades-long mystery. Birders had long suspected that cerulean warblers and parula warblers were mating to create hybrid birds. Although many observers had seen birds that looked like a cross between the two species, or whose calls did not sound quite right, none of the birds in question had been captured for genetic testing.

“Documenting hybridization is important to help us understand speciation, evolution and conservation,” explained Trimbath. “Monitoring and tracking these populations helps inform management practices to protect the species.”

Cerulean warblers are a species of concern across their breeding range, with populations in Ohio declining nearly 75 percent since the 1960s due to habitat loss and fragmentation, as well as deforestation of their wintering grounds in South America. In at least one case, hybridization has resulted in the elimination of a species: blue-winged warblers replaced golden-winged warblers within 20 to 50 years of contact.

Trimbath’s three-year study, internally dubbed “The Secret Lives of Birds,” monitored the nest success rates of three species of forest-breeding songbirds: the hooded warbler, cerulean warbler and the wood thrush. During the course of his work, Trimbath was able to safely collect blood samples from two unusual-looking cerulean warblers in Deep Lock Quarry Metro Park. He then shared the samples with the Cleveland Museum of Natural History, where Dr. Andy Jones and Courtney Brennan conducted genetic testing that confirmed the birds were indeed cerulean/parula warbler hybrids.

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Tracking devices reduce warblers' chances of returning from migration

May 3, 2017

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.


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