PA's New Breeding Bird Atlas Shows Big Changes in Bird Populations

The number of ruffed grouse has declined by 33 percent in the last 20 years--it’s one of a number of victims of nesting habitat loss, says the newly published Second Atlas of Breeding Birds in Pennsylvania.

“It’s the state bird, so that doesn’t quite seem right, does it?” asked Bob Mulvihill during a recent interview.

Mulvihill is the statewide coordinator of the atlas. He served as liaison with thousands of birders, farmers and other volunteers who recorded information they witnessed in the keystone state for several years. Breeding habitat used by the ruffed grouse and song birds has been destroyed by white-tailed deer consuming shrubs low to the forest floor, said Mulvihill.

On the other hand, some birds made new appearances here and are included in the tally of about four million total birds. Mulvihill said that birds in northern forests have done well--expanding their ranges and increasing in abundance. Those birds that live in what are known as successional habitats, where forests or fields are at early stages of development, including the Golden-winged warbler and American Woodcock, have found their habitat curtailed.

“I think the thing that jumps out is the bird species that were completely unexpected,” Mulvhill said. “One is the sand hill crane, which was found nesting.”

The crane, he said, is similar in size to the great blue heron. Another surprise addition to the state’s roster of bird is the merlin, a boreal falcon that had typically been restricted to boreal forests in North America, Mulvihill said. It’s now appearing in the northern tier of Pennsylvania and was also found recently in New York, another state that just completed its breeding bird atlas.

In total, the approximate number of four million birds has remained the same in Pennsylvania, while the species distribution changed.

The 600-page atlas is published by PSU Press and costs $64.95.