Peregrine falcon eggs to hatch on Gulf Tower
Weeks ago, bald eagle watchers couldn’t quite see as eggs hatched in Hays and Harmar. With mounted web cameras unable to peek into nest cavities, hatch confirmation was made by observation of the parents’ behaviors.
This weekend, a camera operated by the National Aviary high atop Downtown’s Gulf Tower is focused to provide close-up live images of the hatching of as many as five peregrine falcon eggs. Peregrine hatchings generally occur at the conclusion of a 32-day incubation period, which many falcon watchers believe will end Monday.
Kate St. John, creator and operator of the Outside My Window peregrine and nature blog (www.birdsoutsidemywindow.org) said her best guess is a Monday hatching, but others think the shells will start to crack Saturday or as late as Tuesday. Watch it directly at http://www.aviary.org/PFNestCam2.
“This is a longtime pair. She’s been there since 2010; he’s been
there since 2003,” said Ms. St. John. “Everybody is excited about [them] — They’re great parents and have raised so many young. They are even happier that [the birds] are on camera and they can see it all happening.”
In peregrine nests, all of the eggs generally begin hatching within a 24-hour period. When the chick inside is ready, it starts banging against the side of the nest with its egg tooth, a sharp knob on the beak that falls off after hatching.
“They make pips — little holes through the shell,” said Ms. St. John. “When the holes open they start breathing air. The holes are all in a line and go around the egg until it opens. It takes about 48 hours.”
If the Gulf Tower peregrine family is stable, the nest site at the University of Pittsburgh’s Cathedral of Learning in Oakland is dysfunctional. Last year during the egg-laying period the female’s mate died — probably in a peregrine-car collision. After eight days another male moved in. But when eggs started hatching, the camera captured an odd saga of life and death that had been rarely witnessed — the female killed two of her four chicks and a third died. She ate them and fed parts to the surviving chick.
“We don’t know why she did that. There are theories,” said Ms. St. John. “Sometimes birds do that under stress or when there’s a chemical imbalance. But it’s very unusual, and of course we were shocked.”
So far, so good at the Pitt site, where four eggs are expected to hatch April 23 or April 24. But peregrine watchers noticed something suspicious.
“Usually the eggs are laid every other day. We noticed a three- or four-day gap between the laying of the third and fourth egg,” said Ms. St. John. “It could go smoothly, but it’s the last egg that was slightly delayed. Last year it was the last [chick] that she ate first.”
You can watch the Cathedral of Learning nest at www.post-gazette.com/baldeagles.