“Crippled reproductively by the pesticide DDT, peregrine falcons stopped nesting in Pennsylvania in the late 1950s,” said Carl G. Roe, Game Commission executive director. “With the banning of DDT in the early ‘70s and reintroduction efforts in several northeastern states — including Pennsylvania — through the ‘80s and ‘90s, peregrines slowly began to reclaim their nesting range throughout the Northeast.”
But there were obstacles along the way. One of the most notable was the great horned owl, which readily preyed on young falcons that were being reintroduced on the cliffs peregrines had nested upon for centuries. Wildlife managers, however, pulled an end-around on the owls: they began reintroducing falcons in urban environments, at elevations where great-horns aren’t as much of a threat. The falcons responded in a big way.
“Since the early 1990s, peregrines have established about two dozen nests in Pennsylvania, mostly on buildings and bridges in the state’s larger cities,” Roe said. “But, in 2003, a pair of peregrines nested successfully on a cliff in Lycoming County. It signaled a new era for Pennsylvania’s peregrines; the birds were finally transitioning to the more than 40 cliffs they had previously nested on.”
In five years, falcons have established three productive “wild” nests in Pennsylvania. Their comeback — considering the number of commonwealth nests — qualifies as a legitimate success story. But from a clinical perspective, it’s still not enough of a recovery to prompt the Game Commission to remove them from the state Endangered Species List. To achieve such action would take about 20 cliff nests.
“We are thrilled that peregrines continue to prosper in Pennsylvania,” said Dan Brauning, the agency’s Wildlife Diversity Section supervisor. “Each new nest strengthens their recovery. But we’d like to see peregrines continuing to return to the cliffs on which they used to nest. This ongoing — and hopefully increasing — natural expansion from urban areas, coupled with the reduction in threats that cliffs offer — will solidify their future and restore one of the state’s most exciting predators to the wild areas they once thrived in.”
Although cities provided peregrines that vital boost needed to launch their re-colonization of the Northeast, they also are home to a variety of mortality factors that greatly exceed the troubles great horned owls may cause wild nests. Windows, traffic and swift river waters are widow-makers and chick-takers for peregrines in urban areas. Conversely, wild nests usually are not located directly over rivers or highways, and glass windows are not as much a part of the rural, wild landscape. In addition, adult peregrines now protect fledgling falcons in the wild.
During peregrine reintroductions, young falcons were released into the wild when they could fly from artificial nest sites, or “hack boxes.” They immediately fended for themselves, but were no match for great horned owls, which snapped them up from outcroppings after dark. Today, as the Northeast’s peregrines continue to move outward from cities into the wide-open cliff country that neighbors rivers, they’re doing so as mature birds. And an adult peregrine takes a backseat to no other bird when it comes to brutish aggressiveness.
Approaching a peregrine nest is like inching out on a tightrope a couple hundred feet up to take a closer look at a nest of angry hornets.
Falcons defend their nests with unrelenting ferocity and in-your-face hostility. Pairs regularly dive-bomb — and occasionally strike — Game Commission officials who approach nests to band the chicks.
To reach the Union County nest overlooking this community, Lycoming County Wildlife Conservation Officer Jonathan Wyant descended about 150 feet to remove one chick from a nest scrape. Brauning followed to assist.
Wyant, who stayed near the nest, was buzzed and verbally assaulted incessantly by the falcons. If he were a great horned owl, he’d have left.
The two-hour operation revealed both parents were not banded and led to the successful banding and health check of the chick, which quickly was returned to the nest.
“From a regional standpoint, it’s a little unusual to have two unbanded adults in a nest, because most northeastern states band all young falcons,” Brauning said. “We hope it means there are more falcons out there than we can account for currently, and that there are more nests for us to find.”
Local birders can be a big help in locating peregrine nests. Allen Schweinsberg of Lewisburg was responsible for finding this Union County nest.
“I knew the cliff was a historic site, so I decided to check it while I was doing fieldwork for the Pennsylvania Breeding Bird Atlas in April two years ago,” Schweinsberg said. “Within three or four minutes after I began watching from the opposite shore, a peregrine flew over me toward the cliff. I revisited several times and eventually saw a pair of immatures in May.”
Schweinsberg, who authored the “Birds of Central Susquehanna Valley,” has followed the falcons regularly since that time.
Last spring, he noticed one of the birds disappeared for about a month in the spring, and eventually concluded she was sitting on eggs. But things apparently didn’t work out for the birds that year.
When Game Commission employees visited the site to band the hoped-for young, they found three nest scrapes on two ledges, but no nestlings or eggs. This year, the birds were active around the cliff since early February, and Schweinsberg eventually uncovered a nest with one chick in it.
“Allen Schweinsberg’s discovery was an important find for us, because it confirms we have another active peregrine cliff nest, which is great news in itself,” Brauning said. “But his find also has led to the discovery that neither of the adult birds had been banded. That finding provides hope Pennsylvania’s — and perhaps the Northeast’s — peregrine recovery is further along that we presume. With a little more time and continuing assistance from the public, we should know more.”
Pennsylvania’s other two known active cliff nests are in Luzerne and Lycoming counties. Falcons also have 22 nests established in cities throughout the state.
Nothing, of course, is certain when it comes to trying to assess the progress of peregrines. Take, for instance, the nest-hopping performed by a pair in Luzerne County over the past several years. The pair took up residence on a bridge. After three years, they moved to a historic cliff ledge. After two years, they returned to the bridge and have stayed there the past two years.
“There may be reasons why this pair has behaved this way, and there may not be,” Brauning said. “There may have been disturbances, or simply something that made the birds uncomfortable at the cliff site. Maybe they’ll return to the cliff some day. At times, what we consider to be best for the birds may not be. There can be a big difference sometimes between observing what seems to be right and living it.”
Peregrines, once commonly called “duck hawks,” are bird-eaters that specialize on pigeon-sized quarries, including flickers, cuckoos, jays and robins. They will prey upon waterfowl, shorebirds and small wading birds, too. Females are larger than males. They can live more than 20 years.
The peregrine’s DDT-induced decline was so devastating that the birds were no longer found east of the Mississippi River by the early 1960s. The insecticide caused falcons and many other birds to lay eggs that were often so fragile they broke when sat upon. Their ongoing comeback is one of the most widely followed stories in wildlife management in the 21st century.
For more information on peregrine falcons, visit the Game Commission’s Web site at www.pgc.state.pa.us, choose “Wildlife” in the left-hand column of the homepage, then click on the “falcon” photo.