A prominent Pittsburgh couple may have something to celebrate.
The eagles of Hays have yet to announce an expansion of the family, but mom and dad appear to be tending to at least one eaglet. No sightings have occurred, but eagle watchers have noticed a change in the birds' behavior indicative of a hatched egg.
Since nesting in February on a steep hillside near the Glenwood Bridge and the Monongahela River, the bald eagles have caused a stir. The nest is clearly visible in the pre-foliage skyline. Eagle watchers gather almost daily on the Three Rivers Heritage Trail near the Keystone Iron and Metal scrap yard.
The male, which frequently rests on a nearby branch, has been hunting more often and bringing more food to the nest. In recent weeks, the female had been less visible, leading some to speculate she was incubating an egg. Over the weekend, she suddenly became more active inside the nest.
"Behavioral changes lead us to believe one or more eggs have hatched, but we're waiting for them to get larger to be sure," said Samara Trusso, Pennsylvania Game Commission wildlife management supervisor for the southwest region.
"You can't see the baby, but there's definitely at least one there," said Robin Weber of the National Aviary, who monitored the site Monday. "We observed the male returning to the nest with food and hopping in. The female was in, and even without binoculars we could see her tail end sticking out. We're assuming she was feeding an eaglet."
"Based on the behaviors we've seen, we should have visible confirmation in the next week, two at the most," Ms. Trusso said.
Henry Kacprzyk of the Pittsburgh Zoo & PPG Aquarium said mid-April is the right time for bald eagle eggs to start hatching.
"Typically, two to three eggs would be normal. If one has hatched, the next would come in a few days," he said.
Following a hatching, a female eagle generally spends most of her time inside the nest, Mr. Kacprzyk said. The male hunts frequently, bringing food back to the female, who takes it into her craw and regurgitates into the offspring's mouth. Fledging, when the young birds leap off the edge of a nest and learn to fly, generally starts in June.
A sign describing the Game Commission's advice for eagle-watching etiquette has been posted near the bike trail. Ms. Weber said people so far have kept a respectful distance.
Mr. Kacprzyk said the most sensitive time for the birds, the mating period, has passed. But if offspring are in the nest, unintentional human behavior could still be disruptive.
"They've apparently gotten used to all the activity," he said. "But if an egg or eggs have hatched, the adults could be driven off often enough that they'd provide insufficient nourishment to the young."
Elsewhere in Allegheny County, eagles have left a nest on a cliff near the Hulton Bridge in Harmar. Ms. Trusso said the original inhabitants of that nest, a pair of red-tailed hawks, have reclaimed it.
Crowds marveled at the aerial display as the eagles and hawks battled for control of the nest.
"Without being able to get inside the mind of an eagle, they must have decided that it wasn't their preferred nesting site and wasn't worth the fight," Ms. Trusso said.
John Hayes: 412-263-1991, email@example.com.