Peregrine falcons are such top predators that adults have few enemies but their young are vulnerable. The parents protect them loudly and vigorously. When peregrines are agitated, everyone knows it.
During the nesting season peregrines monitor for threats and chase them away. They escalate their actions to match the threat level — from a visual show of strength, to shouting and swooping, to direct attacks.
Shouting is important. Peregrines intentionally create a ruckus because the noise calls their mate for assistance, warns their young to lay low, and worries their enemies.
Who is the top threat for peregrine falcons that nest in cities? Humans! When we hear them shouting we get worried. Of course, that’s what peregrines want.
The peregrines that nest in Downtown Pittsburgh — Dori and (not confirmed) Louie — have chosen a site on Third Avenue that’s inevitably surrounded by humans. The birds have a comfort zone that narrows as their chicks grow up. A couple of months ago a human on a roof four stories below them was no big deal. At this point it’s too close.
On Monday a roofer (that we humans couldn’t see from the ground) made repairs on a building several stories below the peregrines. He wasn’t a threat to the birds but they decided otherwise. They flew around, they perched and shouted. Lori Maggio’s photos below show them shouting from Lawrence Hall and from the nest opening. This went on as long as the roofer was up there — until quitting time around 3p.
The photos above are silent but here’s a sample of what they sounded like. The Downtown peregrines were so loud that people heard them from indoors 2-3 blocks away (see this comment from Sandi).
So what happened next? The workman finished and left the roof. The peregrines stopped shouting. Dori joined the chicks at the nest and Lori Maggio got a rare photograph of this year’s chicks, as seen from the Smithfield Street Bridge.
In the end, Dori and Louie probably felt victorious since their shouting appears to have chased off the human. Their chicks learned a valuable peregrine falcon lesson: Humans are dangerous. Keep away!
p.s. Using the chicks’ photo, Art McMorris estimates they were 18 days old on Monday, so they hatched on May 2 and will fledge the 2nd week of June. My prediction is they’ll be completely gone from Third Avenue by June 15.
(photos by Peter Bell and Lori Maggio)