Saving habitat key to songbird's survival

(PhysOrg.com) -- The chirpy buzz of the golden-winged warbler’s song might not sound like a dirge, but it very nearly is one.

The population of this little, gray songbird with bright yellow patches on its wings and head has been in precipitous decline since 1966. And, as of yet, it remains unprotected by the federal Endangered Species Act of 1973.

It’s a dire situation for the warbler, and Ronald Canterbury wants people to know about it.

The golden-winged warbler is a threatened species of songbird because its preferred habitat, like the background setting here, is being invaded.

Canterbury, associate academic director of biological sciences at the University of Cincinnati, has studied the golden-winged warbler for 25 years and last saw one living in Ohio – a place where the bird had been known to breed for at least a century – in 1998. The bird’s range once stretched from the southern Appalachians through the Northeast and Midwest and into southern Canada. Now the largest populations can only be found in Wisconsin, Minnesota and Ontario, Canada; and smaller numbers still exist in the Appalachians.

“If you go to the watch lists, like Audubon or American Bird Conservancy, the golden-winged warbler is going to be in the top 5 and sometimes even the No. 1 bird of critical concern in its breeding range,” Canterbury says.

Canterbury has been studying golden-winged warbler habitats in southern West Virginia for more than 20 years and will have his research paper, “Assessment of Golden-winged Warbler Habitat Structure on Farmlands of southern West Virginia,” published in the upcoming issue of the prestigious quarterly birding journal, The Redstart.

Canterbury has found there are two main threats to the bird’s survival, one you’d expect and one that’s less obvious, but both involve encroachment on its special habitat requirements. The golden-winged warbler is an early successional species, meaning it thrives in areas near the forest edge with a mix of open ground, shrubs and sparse shade trees. It also prefers to live at high elevations. Many areas like this can be found along old coal mining roadways in the mountains of West Virginia

The obvious threat to the golden-wing is man. Modern mining practices favor the mountaintop removal process, where a mountain summit is leveled with explosives to provide easier access to the underlying coal seam. This method destroys a lot of the old mining and logging roads where the warblers lived, leaving a barren plateau.

The other threat is a sister species to the golden-winged warbler – the blue-winged warbler. This bird is similar to the golden-wing in appearance but with different facial markings, a more yellow body and bluish-gray patches on its wings. Blue-wings typically prefer lower elevations but have been spreading up mountainsides and competing with golden-wings, as both birds are naturally territorial.

Key to saving the bird is quantifying how many are left, and finding the remaining critical habitats – places where it is likely to flourish – and preserving them. That’s where Canterbury is concentrating his efforts. He’s been trapping birds in West Virginia, tagging them and tracking their behavior. From what he’s seen, he believes the golden-winged warbler can be saved but time is running out.

“The human population is increasing by the second,” Canterbury says. “The more people there are on Earth, the less there’s going to be available for other wildlife and other organisms. Suburban sprawl is consuming a lot of wildlife habitats, and the golden-winged warbler apparently does not do well in fragmented landscapes.”