On a steep bluff above the Allegheny River in Harmar, bald eagles in Allegheny County's most recently inhabited nest appear to have hatched at least one eaglet.
The Audubon Society of Western Pennsylvania confirmed the hatching Thursday based on behaviors observed through optics from a point near the Hulton Bridge.
Unlike the Hays eagle site, no camera monitors the Harmar nest.
Jim Bonner, executive director of the Audubon chapter, said at least one egg is believed to have hatched Tuesday.
"During the incubation period, the male and female would switch places on the nest," he said. "Six times in the last couple of days, I've observed the male bringing food to the nest, interacting briefly with the female, and leaving. Now, she stays on the nest. Before we saw her head moving in a way that suggested she was rolling an egg or eggs. Now she's up for four to seven minutes at a time, and we see her pulling at stuff as if it's food and moving her head in what appear to be feeding motions."
Audubon observers said something that appeared to be food in the female's beak was gone when she raised her head, suggesting the feeding of an eaglet. She has been observed concentrating her attention on something at the bottom of the nest. The adults' new behaviors began about 36 days after previous activity suggested that an egg had been laid and incubation had begun.
"These are all behaviors consistent with the hatching of one or more eggs," Mr. Bonner said.
This would be the Harmar couple's first hatching. In 2013, the eagles stole the nest from red-tailed hawks, and the eagles were seen engaging in mating activities. But they abandoned the nest. Mr. Bonner said one of the eagles had head coloration that suggested it may have been sexually immature.
A year older, the eagles returned in January, upgraded the nest and were observed mating. Researchers won't be able to determine the level of their reproductive success for about a month.
"We should know in three or four weeks whether there is more than one eaglet," he said. "They'll be big enough that we'll see their heads above the nest."
With construction on the Hulton Bridge, generally heavy traffic on Route 28 and Freeport Road and narrow berms, there is no safe public observation site. The Audubon Society has special permission to watch from a spot just downstream from the bridge.
At Hays, the male eagle has provided ample food from the Monongahela River and surrounding area. The three eaglets that hatched March 28 through April 1 have grown into fuzzy gray balls that alternately eat and sleep, progressing at rate predicted by ornithologists.
Mr. Bonner said it's more difficult to monitor Allegheny County's third bald eagle nest on private property in Crescent. The couple fledged multiple eaglets in 2013 and 2012. They are believed to be in incubation mode.
John Hayes: email@example.com or 412-263-1991.