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Congratulations! You made it to an article covering one of the most fascinating birds, the Peregrine Falcon. These amazing predatory raptors are best known for being the fastest animal and most widespread raptors globally, but there is so much more to learn!
These birds will not leave you unimpressed from their courtship behavior to their killer mustaches. Seeing a majestic Peregrine Falcon soar through the sky or perch in a bell tower will leave you with a healthy amount of fear and admiration for these stunning creatures.
Maybe you’re here because of the news of Grinnell’s death, one-half of the famous Cal Falcons, UC Berkeley’s resident Peregrine Falcons, and want to learn more about the beautiful lives of Peregrines. If you have no idea what I’m referring to, I encourage you to catch up on the remarkable story and tune in to the Cal Falcons Nest Cam, the university’s live feed.
There you can get a bird’s eye view of the action as Annie, a famous female Peregrine, and her new partner, Alden, raise hatchlings. More of this story is shared below.
Continue reading to learn all about their behavior, hunting techniques, relationships, history with humans, and more!
Peregrine Falcon Taxonomy
Also known as the duck hawk, the Peregrine Falcon (Falco Peregrinus) belongs to the order Falconiformes and the family Falconidae, which includes 66 species of falcons and caracaras. Their genus, Falco, consists of the gyrfalcon, pygmy falcon, and American kestrel.
This diurnal bird’s name is derived from the Latin word “peregrinus,” which is translated to mean traveler or pilgrim, referring to the Peregrine’s migratory patterns. As one of the most prolific raptors, there are few places the Peregrine cannot thrive, which means your chances of seeing one in the wild are incredibly high!
How to Identify Peregrine Falcons
To identify an adult Peregrine Falcon, look out for their blue-gray coloring, black nape and crown, pale white throat, and horizontal black barring throughout their underparts. When in flight, adult Peregrines display lightly checkered black and white underwings.
Their key characteristics are their dark black helmets accompanied by sideburns or mustaches that extend below their gray and black-tipped hooked beaks. This dark feathered helmet below their eyes aids in reducing solar glare and bright light conditions when chasing prey.
Juvenile Peregrines have a less distinct brown helmet and different color variations that feature dark brown vertical streaks instead of the black horizontal bars described above. When in flight, juvenile Peregrines display eye-catching checkered brown and white underwings.
Medium in size, this bird of prey reaches 14 to 21 inches in length as an adult and has a 39 to 42-inch wingspan. Peregrines have long pointed wings accompanied by long tails. These fierce raptors are sexually dimorphic, which means females are larger in size than males; however, all Peregrines can be described as “crow-sized.” The average weight of a female Peregrine is about 2 pounds, with most males weighing in around 1.5 pounds.
These strong fliers have cruising speeds of 24 to 33 mph and increase their speed to 67 mph when chasing down prey.
They are seen swooping down quickly, otherwise known as “stooping,” to catch medium-sized birds. Reaching speeds greater than 200 miles per hour, the Peregrine is the world’s fastest animal.
Peregrines can be found perching and nesting on cliffs and tall artificial structures across North America, though they prefer the coasts.
If you are attempting to identify a Peregrine by its call, listen for a raspy “kack-kack-kack-kack” that is only heard near their nesting site.
Where Does the Peregrine Falcon Live?
Peregrines have been found across every continent except Antarctica, making them the most widespread bird of any species. They tend to avoid polar conditions, the rainforest, and intensely hot deserts but can be found in the artic and temperate deserts. They are most commonly found along mountain ranges, coastlines, and river valleys where shorebirds and easy prey are plentiful, and open spaces are common. Search for them around barrier islands, mountain chains, and lakes in the winter.
With the ability to migrate over 10,000 annually between drastically different climates, the climate adaptability of the Peregine is the main reason they can be found around the world.
When nesting sites in their ideal coastal locations become limited or prey becomes light, Peregrines will move into cities and nest on skyscrapers and other artificial structures.
Next time you’re out and about in a major city like San Francisco or New York City and see a flock of pigeons panicking, scan the skies for a Peregrine on the hunt.
Peregrine Falcon Diet and Feeding
As a carnivorous predatory raptor, Peregrine Falcons are primarily sustained on a diet of birds. They have been known to eat 450 North American bird species and around 2,000 bird species worldwide. What type of birds, you may wonder? Well, just about any! The better question is, what isn’t on the menu?
Size doesn’t particularly matter to the Peregrine when making their selection. Every size bird, from cranes to hummingbirds, is fair game for a tasty meal; however, most popular prey includes ducks, doves, shorebirds, gulls, pigeons, and various backyard songbirds like starlings, thrushes, and jays. Even bats, and smaller falcons, including the American kestrel and merlins, are frequently hunted and consumed by the species.
Peregrine Hunting Technique
Popular hunting times are dawn and dusk when other prey is active and open spaces are the key to their mid-flight hunting style success. If a breeding pair has been established, the couple may hunt together, and the female will capture larger prey. Peregrines hone in on birds in flight and use a hunting technique called stooping to dive down at speeds of 240 mph to make their kill.
As the Peregrine stoops 300-3,000 feet, they will fold their tail and wings back while tucking their feet. As the Peregrine approaches its prey, it strikes with a clenched foot. This tactic either stuns the bird or kills it upon impact. The deadly Peregrine will then turn quickly to catch the falling prey. If the target is still alive, they will bite through the neck to kill it entirely. Sometimes the target is too heavy, and in this case, the Peregrine will drop it to the ground before it plucks and eats it.
Peregrine Falcon Breeding
Between ages one and three, the Peregrine reaches sexual maturity. Breeding commonly occurs between two and four years of age but may vary drastically between males and females. Females, on average, begin breeding at three years of age, while males start breeding at four. Peregrines can successfully breed as yearlings; however, these attempts usually result in fewer eggs laid than by adult females.
Peregrine Courtship Behaviors
In an awe-inspiring courtship display, the male Peregrine Falcon will perform a series of spirals, steep dives, and other showboat moves to impress his potential mate. He then catches prey and passes it to the female in mid-air. This act instructs the female to fly upside down in parallel to make the pass successfully. Once the match is made, Peregrines will mate for life (cue the “awws“).
While the Peregrine is generally monogamous, observations of one female occupying the territory of two males have been observed. This behavior is called pseudopolyandry. Similar observations where one male delivers food to two females have also been documented; however, one male breeding with two females will usually result in the neglect of at least one nest.
Peregrine Falcon Nesting
Peregrine Falcons become territorial during the breeding season and aim for a distance of 0.6 miles between nesting pairs. This distance provides a safe guarantee that there will be enough food for the pairs and their hatchlings.
Nesting locations are commonly found on cliff ledges 25-1,300 feet high. If you’re hoping to spot one, look for south-facing sites under overhangs or on ledges with vegetation. If a cliff ledge is not available, it is customary to find Peregrines nesting on skyscrapers, silos, bridges, and other highly elevated locations.
Large tree hollows are also used as nesting sites in parts of Australia and northwestern North America. When no cliffs or suitable nesting locations are available, the use of other species’ abandoned nests will do. These species most frequently include ravens, eagles, osprey, and red-tailed hawks.
A Peregrine nest is called a scrape. It is not your traditional collection of sticks and dog hair you may typically see in your backyard, but instead is a depression in the substrate, sand, or gravel about 9 inches wide by 2 inches deep.
A male Peregrine Falcon will scout out a few nesting locations he finds sensible. Once he’s found some prime real estate, the female will select the final nesting location, and the pair will defend their turf against other Peregrines, ravens, gulls, and herons.
Peregrine Falcon Eggs
While the months vary by region, most female Peregrine Falcons lay eggs from February to March in the Northern Hemisphere. In the Southern Hemisphere, July to August egg-laying is common.
A female may lose her eggs early in the nesting season. When this occurs, she will typically lay another clutch. A Peregrine’s clutch may be anywhere from three to five white eggs with red or brown markings. The eggs have an incubation time of 29 to 33 days, and while the incubation is the primary responsibility of the female, the male will assist with incubation duty during the day.
Although a female may lay three to five eggs, the average number of chicks per nest is 2.5, and only half of those actually leave the nest due to natural causes. Chicks have whitish-down feathers, closed eyes, and weigh around 1.5 ounces upon hatching.
Chicks are dependent on their parents for two months and make their giant leap into the world around days 42 to 46. Both mom and dad leave the nest to hunt and supply their new bundles with sufficient resources. The hunting territory of a Peregrine can extend 12 to 15 miles from the nesting site.
Peregrine Falcon Population
Currently, the global breeding population of Peregrines is estimated to be 340,000. The Continental Concern Score ranks the vulnerability of land birds and ranks them on a scale between 4 to 20. The Peregrine was ranked 9 out of 20, indicating low conservation concern.
Current Threats to Peregrine Falcons
Everyday threats to the Peregrine Falcon species include illegal trapping for use in falconry practices, rock climbing, habitat degradation due to woodcutting, climate change, fire weather, pesticide use, collisions with cars, electrical cables, and other manmade structures.
Is the Peregrine Falcon Endangered?
Along with the rise of organochlorine pesticides in the mid-20th century, the Peregrine population reached critical numbers between 1950-1970. By 1975, only 324 nesting pairs of Peregrines were known to exist. DDT poisoning depleted the eastern population, causing them to be listed as Endangered Species.
How do pesticides and the decline of the Peregrine population correlate? Well, the increased use of pesticides meant that organochlorines began to build up in the fat tissue of Peregrines. This resulted in a reduced amount of calcium in their eggshells. This meant that fewer laid eggs survived the incubation period; thus, fewer broods were born per nesting pair.
This steep rise in population is due to bans on pesticides and the conservatory work performed by Tom Cade at the Cornell Lab of Ornithology, which is known today as The Peregrine Fund. In 1999, Peregrines were lucky enough to be removed from the Endangered Species List.
Peregrine Falcon Habits
Cal Falcons of UC Berkley
In April 2022, we were able to witness some fascinating Peregrine behavior when Grinnel, a famous male Peregrine Falcon studied by avid birdwatchers and UC Berkley students, tragically died. It is believed that he died defending his nest from a juvenile Peregrine looking for a quick snack; although a car is the ultimate cause of his death, the fight took the dual dangerously close to traffic.
When Grinnel died, the fate of his nest with Annie, his lifelong partner, was up in the air. It is not unordinary for females to abandon the nest when a male partner is not there to deliver prey or offer nesting support.
Those captivated by Annie and Grinnel’s partnership feared abandonment would be the case because Annie had been known to disappear for days or weeks at a time. Within just a few days, a new unidentified male began a courtship with Annie. Once the courtship appeared to be final, the new guy in the picture was given the name Alden.
Observers were unsure if Alden would adopt the eggs present in Annie and Grinnel’s nest, but we were all pleasantly surprised to see him deliver meals and even incubate the eggs in Annie’s absence.
While tragedy strikes from time to time, the resilience and acceptance displayed by these two Peregrines was truly beautiful.
Peregrines are not known to be particularly social with one another unless it is during the breeding season. Peregrines that migrate during the winter season spend eight months of the year on their own, only interacting with a mate for 16-18 weeks to raise their hatchlings. Non-migratory Peregrines will live solo or spend time with a mate if they have found one.
Familial relations are not a big deal for Peregrines, and they don’t reunite with their young after they have taught them to be self-sufficient. Once the skills of hunting and flying have been learned, the offspring must leave the territory and fend for themselves. There is also no recognition of shared bloodlines between Peregrines if they encounter one another in the wild.
Peregrines hunt within a 15-mile radius, but this varies due to the hunting success of each bird. Perching at a high vantage point to observe the activity of prey is common.
Food is consumed away from the eyrie in two main locations, either where the prey was captured or at a preferred perching spot such as a tree, rock, or another area where Peregrines can avoid humans.
During the breeding season, a food cache is kept for prey. This reduces the need to hunt throughout the day and devotes attention to the nest.
Peregrine Falcon Predators
While the Peregrine is a raptor to be feared by all medium-sized birds, its small size makes it a target for larger raptors and carnivorous birds such as eagles, gyrfalcons, and great horned owls, and larger predatory mammals like bears and wolverines.
Adult Peregrines can pose a threat during nesting season to young Peregrine hatchlings. Other nest predators include red foxes, gray wolves, great horned owls, red-tailed hawks, and ospreys. In order to defend their nests, Peregrines will face off with predators to scare them away from their nests by stooping at unwanted guests.
Male Peregrines have been documented attacking fledglings of their own. Eating offspring is primarily observed when the nestlings have perished due to unrelated causes.
Peregrine Falcon Lifespan
The mortality rate during the first year of life is 59-70%. After that, an adult Peregrines’ chances of survival increase significantly, and mortality rates decline to 25-32%. The average lifespan of a wild Peregrine is 13-19 years. The longest recorded lifespan of a captive Peregrine is 25 years.
Peregrine Use in Falconry
Falconry is the sport of utilizing falcons or other birds of prey in hunting practices. Initially established in Central Asia over 3,000 years ago, humans have benefited from the existence of these marvelous birds.
The Peregrine displays extreme athleticism along with a high prey drive, versatility, and desire to hunt, making the bird a prime candidate for falconry training. Smaller male and female Peregrines are preferred by falconers for hunting birds like doves, quail, and small ducks. Larger females are ideal for the hunting of large game like grouse, pheasant, and large ducks.
While previously captured in the wild for use in falconry, Peregrines are now successfully bred in captivity, with some being released into the wild for repopulation efforts. Falconers are credited with massive repopulation efforts when the species was listed as Endangered.
Relationship to Humans
While humans have been successful in capturing Peregrines, this has resulted in the Peregrine’s fear of humans. While responsible falconers treat their Peregrines with respect and compassion, it doesn’t take long for a species to figure out that our involvement in their lives leads to harmful circumstances, like captivity and poisoning. Human interference within a Peregrine Falcon’s territory can result in aggressive behavior from both male and female falcons.
Peregrine Falcon FAQ
Answer: Yes. The Peregrine is commonly referred to as the world’s fastest bird and animal. Their cruising speed averages between 25-60 mph. When stooping in pursuit of prey, Peregrines can dive at speeds over 200 mph.
Answer: While the Peregrine species was active on the Endangered Species List from 1969 to 1999, 30 years of drastic repopulation efforts, protective laws, and pesticide bans led to an increased population and their removal from the Endangered Species List.
Answer: Yes. If they interfere with a Peregrine’s nest or territory, humans are at risk of being attacked by a Peregrine Falcon. Instances of conservationist and rock climber attacks are most reported. Always avoid a Peregrine’s territory and choose a safe distance to observe their behavior safely. This practice is essential to remember for all wild animals.
Answer: Once hatched, a baby Peregrine Falcon is called an eyases. Males are called “tiercel,” and females are called “falcon.”
Answer: A Peregrine Falcon can see at least one mile and is able to focus on three moving objects at once. The structure of their eye is frequently compared to a telephoto lens.
Luensmann, Peggy. (2010). Falco peregrinus. In: Fire Effects Information System, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Retrieved May 29, 2022, from www.fs.fed.us/database/feis/animals/bird/fape/all.html
Cornell Lab of Ornithology. (n.d.). Peregrine Falcon Identification. All About Birds. Retrieved May 29, 2022, from https://www.allaboutbirds.org/guide/Peregrine_Falcon/id
White, C. M., N. J. Clum, T. J. Cade, and W. G. Hunt (2020). Peregrine Falcon (Falco peregrinus), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.perfal.01
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