PA Fall Bird Migration An Aerial Pageant
Nature lovers taking in Pennsylvania's fall foliage only have to look up a little farther for another amazing display, as flocks of birds make their autumn migration over the state.
An expert in Penn State's College of Agricultural Sciences explains why the Keystone State enjoys a unique position in the procession.
Birds have good reason to be drawn to the state, according to Margaret Brittingham, professor of wildlife resources. "Pennsylvania's ridges and mountains create excellent updrafts for golden eagles and other soaring raptors," she says. "Particularly the raptors are coming down those ridges, following the mountain lines and riding the currents as the fall winds hit those mountains. Recently we've discovered that we're an important state for golden eagle migration - central Pennsylvania has the highest concentration of migrating golden eagles east of the Mississippi River.
"The other thing that's good about Pennsylvania is that we still have a lot of forest habitat, and while many states have lost a lot of the birds associated with forest habitat - such as scarlet tanagers or wood thrush - or have seen really great declines in numbers, we still have healthy populations of those species."
Pennsylvania's birdwatchers have been enjoying the fall avian spectacle for a century or more, Brittingham notes. "We certainly have a long history of bird-watching," she says. "Wildlife artist and naturalist John Audubon did a lot of his collecting here, and Alexander Wilson, who's called the father of ornithology, is from right outside of Philadelphia. So historically, it's been a very important state for bird-watching, and we've got a lot of very famous places such as Hawk Mountain, where birders have gathered to watch migrations since the early 1900s."
Bird-watchers and casual observers in Pennsylvania have noted what they believe to be a decline in the numbers of birds in recent years.
Brittingham explains that, while total numbers of birds in the state haven't dropped, species that raise their young here then migrate to winters in Central and South America have.
"Declines of migrating birds have been pretty widespread and are probably due to changes both here on the breeding ground and on the southern wintering ground," she says. "Migration hazards such as buildings erected in their traditional flight paths and development along the Gulf Coast in areas where birds once rested and fueled up are creating real challenges. A lot of problems occur with buildings on foggy nights if migrating birds are flying low and can't see; that's when they run into them."
Happier news, says Brittingham, is that bald eagles and peregrine falcons are making a comeback in the state. "These birds had been severely impacted by DDT pesticide use. When DDT was banned in the United States, they started to bounce back. Now, Pennsylvania birders can see the results for themselves."