My Favorite Interesting Facts About Peregrine Falcons

By the middle of the twentieth century, the peregrine falcon was placed on the Endangered Species List, due to a sharp decline in its population. This decline was caused by DDT pesticide contamination, which caused their eggshells to be so thin that they would break when the adults tried to incubate them. In 1999, due in part to bans on the usage of DDT, and breeding and reintroduction programs designed by falconers and raptor biologists, the peregrine was removed from the endangered species list. Despite this, most people have never seen one in the wild. I myself have only seen them twice. When I first saw one, I was stunned by the beauty of this streamlined, black and blue-gray bird that was lying on a cliff across the Yellowstone Canyon, incubating her eggs. In this blog post I am sharing six of my favorite facts about peregrine falcons.

The black and blue-gray feathers on Hayabusa’s back.

The black and blue-gray feathers on Hayabusa’s back.

1) Often the first comments I get from visitors when they see Hayabusa, our peregrine falcon, is that she is so stunningly beautiful, and her eyes are so large. According to the book Peregrine Falcon by Patrick Stirling-Aird, if our eyes were the same proportion to our bodies as a peregrine’s, our eyes would be 3 inches across and weigh 4 pounds each.



2) The peregrine’s large eyes are incredible tools which help them survive in the wild. They can see at least one mile and keep track of three moving objects at one time. Within the eye, peregrines have a fovea center (focal point on the retina) at the back of each eye, which is similar to a telephoto lens. These are used independently of each other for viewing two different distance objects, one with each eye, as they turn their head from side to side. Shallower focal points in each eye work together to give the peregrine binocular vision, similar to ours, allowing them to see one central image. Therefore they can visually keep track of one central binocular image like we do, and two magnified images, one for each eye.

Hayabusa showing her streamlined body shape.

Hayabusa showing her streamlined body shape.

3) When you see a peregrine falcon, you are looking at what is typically considered the fastest animal on the planet. Depending on what reference you read, peregrines can fly at speeds of 65 to 70 miles per hour. Cheetahs, the fastest land animal, can run at speeds of 70 to 75 mph for short distances. So what makes the peregrine the fastest animal on the planet? It is their dive, called a stoop. With their teardrop body shape and their compact feathers these stream-lined birds slip through the air with little resistance once they fold in their wings. Researchers have discovered that the peregrine can dive at speeds over 200 miles per hour. One group of researchers clocked their research falcon diving at an incredible 242 miles per hour. Not many other animals can compete with that!

Below is an excellent video highlighting these amazing stoops:

4) A potential flight hazard to a bird that can dive over 200 miles per hour would be that, while breathing, pressure could build up inside its. Some sources believe that this pressure could possibly cause the lungs to burst. The peregrine falcon, however, has evolved with a nostril structure called a tubercle that deals with this problem. The tubercle is a bony conical structure that acts like a baffle, causing the air to curve in a spiral manner rather than rushing straight into the lungs. This slows down the air as it enters the peregrine’s nostrils, therefore allowing the peregrine to breathe normally and safely at high speeds.

Check out the 2nd photo in this blog for another view of the tubercle.

Check out the second photo in this blog for another view of the tubercle.

5) 77 to 99 percent of a peregrine falcon’s diet is other birds, and their favorite way to make their kills is to use their speedy dives to strike their prey while it is in flight. When the peregrine spots its prey, it will often begin its dive in a circular manner, which allows them to keep track of the prey without the drag of an additional head movement. The peregrine then closes up its wings and plummets toward the earth. As they approach their prey, they will turn up slightly in preparation for the kill. As they do this, peregrines are able to withstand the force of 25 Gs. (Humans will pass out at 9 or 10 Gs.) At this point, the peregrine will usually ball up its feet and, while flying past the prey, attempt to strike the prey in its head. If the hit is successful, it will often kill the targeted bird outright. If the prey survives the strike, the hit will stun it, causing it to fall to the ground, which will usually kill the bird. In the event that the fall does not do the job, the peregrine uses its tomial tooth, a sharp structure on its upper beak, to snap the vertebrae of the prey. Peregrine falcons have been seen attacking birds as large as geese, pelicans, and even blue herons.

But how successful are they? Unfortunately they do not have a high success rate. According to a BBC documentary film, only 20 percent of their high speed dives end in a successful kill.

6) And here is the latest on peregrine falcons that really blows my mind! Falcons are genetically more closely related to parrots than hawks! In early 2012, their scientific order was moved next to the order of parrots. Although you can’t see Haybusa’s DNA as she stands upon my glove, there is a visual similarity you can see. Parrots and falcons both have the sharp tomial tooth on their beaks, which hawks and eagles lack. My parrot Chiquita’s tomial tooth looks just like Hayabusa’s.

Chiquita’s tomial tooth.

Chiquita’s tomial tooth.

Question from Visitors:

Why does she shake like that?

Hayabusa often raises her feathers, and shakes. This is called a rouse, and is done to shake the feathers into place, as well as to remove dust and debris. A captive bird will only rouse on a glove if they are comfortable with the situation.

Hayabusa getting ready to shake out her feathers.

Hayabusa getting ready to shake out her feathers.


  1. Jen says

    Great, interesting facts!! Thanks for this awesome post. 🙂

    Haya is so gorgeous. 🙂 What kind of parrot is Chiquita? What a cutie. 😉


  2. mike schuster says

    Anne, your post gave me a new appreciation of peregrines. With their incredible eyesight and their high speed impact when killing prey, it’s obvious why their eyes and feet are so large in proportion to their bodies. Too many interesting facts to mention, but thanks for taking the time to educate us about Hayabusa and the other ‘stars’ of the Raptor Experience. Excellent writing as usual!

  3. says

    Thanks Mike, glad you found a new appreciation for one of my favorite birds. Peregrines are truly amazing, and they, as well, as their small relatives, the male kestrel, are absolutely stunning to look at.

    • mike schuster says

      > > Peregrines are truly amazing, and they, as well, as their small relatives, the male kestrel, are absolutely stunning to look at. >

      Is that a hint?

      • says

        I don’t quite understand what you mean by your question. If you are asking if I am hinting that for me peregrines and male kestrels are my favorite falcons, then I would have to say in my opinion all falcons are beautiful, including the female kestrel, though the two I mentioned are the most colorful in the Yellowstone area. I saw my first ever prairie falcon in the wild this year, and it was such a thrill. If you are asking if I would like a kestrel for our program, I have a long list of birds I would like to have standing on my glove, including hawks, owls, and other falcons. I love all our birds, and having any of them with me is still an unbelievable experience. I would have never even imagined I would ever have the opportunity to become a raptor handler. But even so, it would be pretty exciting to have additional birds. I wouldn’t, however, want more than we need. I would hate to have so many birds that a lot of them are standing around, rarely being used.