Outdoor Radio: Peregrine Falcons On The Bolton Cliffs

May 21, 2015

Biologists Kent McFarland and Sara Zahendra of the Vermont Center for Ecostudies recently took a trip to the Bolton Cliffs in search of a mighty bird.

“Today we drove up just a few miles from the interstate to see something that’s faster than a speeding train and able to leap the Green Mountains in a single bound,” says McFarland.

“The peregrine falcon,” replies Zahendra.

The peregrine falcon is one of the fastest birds in North America, says McFarland.

They agree that the trees have greened up “just right” so they still have a pretty good view of the cliffs.

Margaret Fowle, from Audobon Vermont, joins the biologists in Bolton to talk a bit more about what makes these particular birds so spectacular. 

“Margaret’s got a good scope set up for us. Let’s get up on the road where we can get a good peak over the trees and up at the cliffside,” says McFarland.

Zahendra asks Fowle why the peregrines are sitting on the cliffs.

“They like to be in high places with views of their surroundings,” answers Fowle. “They are very territorial species, so they like to be able to see potential intruders that might come by, which could be another raptor, a hawk … or a raven. And they defend the cliff against these birds.”

"They like to be in high places with views of their surroundings. They are very territorial species, so they like to be able to see potential intruders that might come by." - Margaret Fowle, biologist at Audobon Vermont

McFarland adds, “The neat thing about this place, though, is that the parking lot is right here off of Bolton Notch Road, so anybody could come here and stand at this parking lot and maybe get a look at these peregrines.”

Fowle agrees that it is an exceptionally accessible cliff. “Not every cliff in Vermont is so easy to see or to get to, so this place is great for trying to get a peak at these birds,” she says. “And we’re doing it at a distance, we’re not anywhere near them, so we’re not disturbing their activities.

Biologists Margaret Fowle, left, and Sarah Zahendra look for peregrine falcons in Bolton. The high wind can make it harder to listen for, and see, the large birds.
Credit Kent McFarland

“What’s the easiest way to see where the birds are nesting?” asks Zahendra.

“It’s really hard. You really have to be patient,” says Fowle. “Watching peregrines is almost like watching paint dry. They are constantly trying to conserve their energy so they are spending a lot of time resting on the cliff, just taking a break. Hunting for them takes up a lot of energy.” She adds that they can dive up to 200 miles per hour once in flight.

“This is, what I think, one of the coolest things about peregrine falcons. They dive at up to 200 miles per hour,” says Zahendra.

Fowle says the birds gain altitude by soaring up into the area searching for potential prey. She notes that general prey for a peregrine is a medium-sized songbird such as a robin or blue jay. “And once they see their prey, [and] they’ve got great eyesight, they tuck their wings in and they’re almost shaped like a torpedo. They just dive, free fall after these birds in flight,” explains Fowle. “Once they get close to it, they’ll hit it with their feet, knock it out with their feet, and then pick up that bird as it’s falling, and that’s how they catch their prey.”

The conservation biologist says that at this point in the year, the male usually does all of the hunting and the female usually stays at the cliff. “She is either on the nest site incubating eggs or taking care of the young, while the male hunts,” she says. “Then when he comes back with prey, she’ll come off the nest to eat and he’ll incubate or take of the young for her while she takes a break.”

“Let’s take a break and get a look at her sitting on the nest,” says McFarland.

"Watching peregrines is almost like watching paint dry. They are constantly trying to conserve their energy, so they are spending a lot of time resting on the cliff, just taking a break."

“It’s actually not a nest,” explains Fowle. “It’s a flat ledge. She’s probably scraped a little depression to lay her eggs in, and hopefully it’s got some cover from weather. Hopefully it’s on a part of the cliff that isn’t accessible by predators that can walk up there, like a raccoon or something like that.”

McFarland wonders if the birds bring material in to build the nest on the cliff.

Fowle explains that peregrines don’t do any nest-building. “They might use an old raven nest that a raven built and they have done that here before,” she adds.

In the late spring, female peregrines usually stay home to tend to their young. When the male comes back from a hunt, he'll take over watch so the female can have a break.
Credit Steve Faccio

“We’re fighting with a little bit of wind today, does that make it harder for us to spot these birds up in the cliff, or [do they not care]?” asks McFarland.

Fowle says that the peregrines don’t care about the wind. “It’s harder for us, as the observers, because I often rely on sound to hear them, so when it’s really windy it’s hard to hear them and it’s hard to look through the scope when it’s windy," she says.

Fowle scans the cliff and sees one of the adults perched. McFarland and Zahendra exclaim with excitement.

“I can sometimes tell the difference between the male and the female, but it’s just a size difference. They look the same,” says Fowle. She explains that the female peregrine is typically larger than the male.       

“I can see this bird,” says Zahendra, looking through the scope. “She keeps turning her head around and you can see the yellow on her face. She’s beautiful. She has a dark facemask and yellow on the rest of the face.”

"The ravens share the cliff with the peregrines. Their nest is lower on the cliff. There is often a territorial dispute with the ravens and the falcons — there's some imaginary line that they've drawn on whose side of the cliff is whose." - Margaret Fowle

“The ravens share the cliff with the peregrines. Their nest is lower on the cliff. There is often a territorial dispute with the ravens and the falcons — there’s some imaginary line that they’ve drawn on whose side of the cliff is whose. But the peregrines are usually in charge of where the line is,” says Fowle.

Zahendra says that where she lives, she has been seeing signs that say people can’t go beyond a certain point due to peregrine nesting. “What is it that hiking on the trails is going to do to the peregrines, why are the trails closed off and how long are they closed off for?” she asks.

Fowle says they close about 10 of the 40 sites in Vermont that they consider to have a high disturbance potential. “These are either cliffs that people like to rock climb on or they are cliffs that have an overlook that is right above the peregrine nest, she says. “Peregrines are pretty tolerant of activity below them, but they’re not really tolerant of activity on the cliff or near their nest site on the cliff or above them on a cliff.” She adds that repeated disturbances, or long disturbances, to the nests could cause the birds to abandon their nest site.

“Will they stay here year-round, and is it the same birds coming back year after year?” asks McFarland.

“The peregrines in Vermont do a lot of different things during the winter. Some will stick around and it’s really dependent on the availability of food,” says Fowle. “So if they can’t find food in Vermont, which is pretty scarce in a winter like the one we just had, they might move down to the mid-Atlantic or somewhere where they can find food. Generally the same pair comes back to the cliff in the spring after spending the winter somewhere else.”

McFarland and Zahendra point out that the peregrine falcon at one point disappeared completely from the East.

"In the late '70s and early '80s we released over 90 birds at three different hack sites, and the hope was that they would come back to somewhere nearby to breed. And that's what happened."

“The main cause for their decline and going extinct in the East was DDT, a pesticide that was used to get rid of bugs on plants," says Fowlke. “It ended up having a really bad effect on a lot of different bird species.”

Fowle explains that biologists re-introduced the birds through a process called hacking. “In the late '70s and early '80s we released over 90 birds at three different hack sites, and the hope was that they would come back to somewhere nearby to breed. And that’s what happened,” she says.

In 2005, peregrine falcons were taken off the Vermont endangered species list.