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.