Meet the peregrine falcon

Photo by Mykola Swarnyk. Retrieved from Wikipedia on 07-20-2023. Shared under CC BY-SA 3.0.

It’s been an exciting month at work – we’ve had juvenile peregrine falcons hanging around! The parents have a nest in the building across the street from us, and the babies have apparently decided that the balcony on the 15th floor is a great place to chill. It’s been so cool to get to see these birds up close!

Two of our friends. We know they’re juveniles from the streaking on their chest. Photo by Topher Dial.

Peregrine falcons (Falco peregrinus) are the world’s most widely distributed bird of prey. You can find breeding populations on every continent (except Antarctica – that’s one place it gets too cold!).

Like many raptors, peregrine falcon females are larger than males. This size difference gives us the names for male and female falcons – males are roughly 1/3 smaller than females and are called ‘tiercels,’ while females are just called ‘falcons.’

World travelers

Peregrine falcons are known for their ability to travel long distances. In fact, their name, ‘peregrine,’ comes from the Latin word peregrinus, meaning ‘wanderer’ or ‘pilgrim.’

Not all peregrine falcons migrate, but those that do are capable of impressively-long migrations. Some populations will nest on the Arctic tundra yearly and fly as much as 15,500 miles to South America for the winter. These migratory peregrines will return to the same nests year after year; some nesting sites have even been used for hundreds of years over generations.

Aerial hunters

Peregrine falcons are so widely spread in part because they’re not very picky when it comes to food. As aerial hunters, they thrive in hunting other flying prey and attack mid-flight. But as far as the actual species they go after, peregrines aren’t very fussy – if they can see it and catch it, they’ll eat it.

Their primary food source is other birds, and peregrines are thought to hunt several thousand different species of birds worldwide. North American peregrine falcons have been documented eating around 450 species of birds. Generally, peregrines go for small- to medium-sized birds but have been seen eating ones as large as a sandhill crane.

Photo by Juan Lacruz. Retrieved from Wikipedia on 07-20-2023. Shared under CC BY-SA 3.0.

In addition to birds, though, peregrine falcons will hunt bats and aren’t above the odd reptile or two. Peregrine falcons are also known to pirate prey from other raptors and have been seen eating fish and rodents.

Peregrine falcons are capable hunters in part because of their impressive vision. It’s estimated that peregrines can see eight times better than us, and these birds can spot prey almost two miles away. To protect their eyes during flight, peregrine falcons have an extra, partially translucent eyelid and special skull bones that help keep their eyes in place when moving quickly.

They’re fast…very fast

Peregrine falcons are speedy fliers, averaging about 25-34 miles (40-55 km) per hour when traveling. This shoots up to 69 miles (112 km) per hour when they’re actively pursuing prey.

But it’s their diving flights, called ‘stoops,’ where peregrine falcons get their real speed. By flying high and then diving, peregrine falcons can reach speeds of more than 200 miles (320 km) per hour; this makes them the world’s fastest animal.

And believe it or not, most animals don’t do well after getting hit by a feathery bullet. Peregrines will strike during their stoop with clenched talons. If this impact doesn’t kill their prey, the resulting fall to the ground usually does.

And if somehow their prey is STILL alive, peregrines will use their beaks to finish the job. Unlike some other birds that use only their talons to kill, peregrine falcons have a ‘tooth’ at the end of their beak to sever necks. This tooth (known as a tominal tooth) is a notch on the peregrine’s upper bill that can break an animal’s spinal cord.

According to Bird Watching Academy, a peregrine falcon’s stoop could theoretically break our spinal cord. (Key word there is ‘theoretically’ – it’s never happened before!)

How do they breathe?

Diving at such high speeds comes with some dangers, namely lung damage from changes in air pressure. Pressure could build inside a peregrine falcon’s lungs while diving, potentially ending in a burst lung.

Peregrine falcons have evolved tubercles (small, bony protuberances) in their nostrils to deal with this change in air pressure. These tubercles serve as a small obstacle for incoming air, reducing its speed as it enters the lungs. The tubercle acts like a baffle, making the air spiral into the lungs instead of rushing straight in.

The dot in the nostril is the tubercle. Photo by Greg Hume. Retrieved from Wikipedia on 07-20-2023. Shared under CC BY-SA 3.0.

Peregrine falcons have also evolved a very efficient respiratory system in general. A one-way airflow system keeps their lungs inflated via air sacs even when they exhale; this allows them to still breathe and get oxygen to their lungs when diving at high speeds. In addition, a heart that beats between 600 and 900 times per minute keeps blood and oxygen flowing throughout the body. Because of this, a peregrine falcon can flap its wings up to four times a second.

City life

The traditional habitat for peregrine falcons is rocky, open country with cliffs. Their nests are called ‘scrapes’ and are basically just that: a scrape in the dirt on a cliff edge.

Do you know what else works as a high cliff? Skyscrapers! Peregrine falcons have adapted very well to the rise of human cities and may nest on the top of tall buildings. The peregrines around our building seem to have taken a liking to eating all the pigeons that can be found around Boston.

Peregrine falcons typically lay three to four eggs in their scrapes, with their young hatching about a month later and fledging five to six weeks after that. But the parents aren’t done with their children after fledging. Juveniles typically stay with their parents for about two months while they learn to hunt.

It looks like our young peregrine friends will be around for about another month before they fly off to find their own homes!

Peregrine friend! Own photo.



National Geographic

Smithsonian Magazine

Australian Museum

All About Birds


Peregrine Fund

National Park Service

Discover Wildlife

The Nature Conservancy

Center of the West

UMass Amherst

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