Peregrine falcon that lived in Manayunk steeple found dead with severed leg. Did a drone do it?

Judy Stepenaskie, an amateur but avid bird-watcher, was thrilled in 2011 when a pair of peregrine falcons began nesting in the steeple of St. John the Baptist Roman Catholic Church in Manayunk.

The birds of prey had been all but eradicated in the Philadelphia area for decades but were making a comeback at the time. Having a pair locally gave Stepenaskie a rare chance to observe them up close for years.

So Stepenaskie was crushed last week to learn that the 10-year-old male, whom she had been calling Manny after his adopted hometown, turned up dead. Mysteriously, his leg was cleanly severed. Peregrine falcons live high up and face few real predators in an urban environment.

“I was really upset. It’s really sad. He was such a good dad,” Stepenaskie said in reference to Manny’s vigilance each time his mate gave birth over the years.

Mike Weilbacher, executive director for the Schuylkill Center for Environmental Education in Philadelphia, said the bird was brought to the center’s wildlife clinic on Sept. 11 after a woman had found it in her yard in Roxborough.

“It was unusual because the leg was severed so cleanly,” said Weilbacher. The clinic is still awaiting a necropsy expected to be performed by the Pennsylvania Game Commission, so an immediate cause of death was not yet available. The bird is being preserved in a freezer at the clinic.

Some are speculating whether the bird might have flown into a drone.

Stepenaskie said she has seen drones flying in the area of the steeple recently. And, there are drone postings on Facebook of flyovers in that area.

However, she noted she does not know whether it is even possible for a drone’s rotors to cut through the bird’s leg. She does know that peregrine falcons are quick to attack perceived threats to their nesting areas or mates.

At 15 to 22 inches long, peregrine falcons are medium-sized birds of prey with wingspans of more than 3 feet. They are listed as threatened and protected under the state’s Game and Wildlife Code. The bird was removed from the federal Endangered Species List in 1999, but it is still protected under the federal Migratory Bird Treaty Act.

Peregrines, though native to the eastern United States, were never present in big numbers. In the early 1900s, there were about 44 known nest sites in Pennsylvania, mostly on remote cliffs along rivers. But the population was wiped out by the 1960s because of the insecticide DDT, which was banned in the 1970s.

Since then, the bird has made a dramatic recovery with nest numbers close to what they were before DDT.

But now, most peregrines are nesting on buildings and other man-made structures. There have been nests reported at Philadelphia City Hall and area bridges.

Male and female falcons pair for life, with females laying about five eggs in a season. The pair share incubation duties for about 31 days.

What will happen to the surviving female?

According to Art McMorris with the state Game Commission: “St. John the Baptist is a prime nest site, and the female will surely stay and attract a new mate. … Even if she doesn’t attract a new mate that quickly, she is sure to … next year, and life will go on.”

Said Stepenaskie: “This past year I saw another male fly in and actually try to mate with the female. She brushed him off, and when he tried again, she chased him, then Manny flew up from a block or two away and chased the male off.”

Peregrines eat other birds, and so Manny and his mate typically feasted on the pigeons that originally inhabited the steeple. Parishioners have stories of seeing severed heads of birds on the ground. A call to the church was not returned.

Both Manayunk birds had been banded and tracked their entire lives, so their origins are clear. Manny was born on the Girard Point Bridge that crosses the Schuylkill in Philadelphia. Stepenaskie called his mate Liz because she was born in 2008 in Elizabeth, N.J., atop the Union County Courthouse.

Stepenaskie has been chronicling their lives since they took up residence in Manayunk, and said the pair had produced three to four offspring each year.

“We see them flying around in the air performing mating rituals,” Stepenaskie said.

She’s also seen a drone flying by two separate times.

“I saw a person post pictures on Facebook that his drone took over the church steeple,” Stepenaskie recalled. “So I posted asking people to not fly their drones there.”

Patty Barber, a biologist with the state Game Commission, said she has not seen a documented case of a peregrine falcon being killed by a drone, but said it’s become an international concern.

“We have lots of video evidence of raptors going after drones," Barber said. “So that is a real thing. And you are not supposed to be flying drones anywhere near a nest. Nests have a no-fly zone over them. Anything a bird can collide with is potentially dangerous.”

Barber said the only natural predator a peregrine falcon might face would be a great horned owl. But it seemed unlikely an owl attack would sever a leg. Other man-made objects, such as wires, do have potential to sever bird limbs, she said.