Eagles are some of the largest and most powerful birds of prey in the world. As apex predators, they sit at the top of the food chain and have very few natural enemies that would threaten them. However, there is one smaller bird that is fearless enough to actually attack an eagle under the right circumstances: the peregrine falcon.
The Peregrine Falcon
The peregrine falcon (Falco peregrinus) is renowned as the fastest animal on earth. These small but mighty falcons can reach speeds of over 200 mph when diving for prey. They have slim, aerodynamic bodies and long, pointed wings which allow them to achieve these incredibly fast speeds.
Peregrines are between 12-21 inches in length with a wingspan of around 3 to 4 feet. They have blue-gray upperparts and barred undersides ranging in color from cream to rusty brown. Their most distinctive feature is the dark helmet-like markings on top of their heads.
These powerful predators are found on every continent except Antarctica. They thrive in many types of habitats including coasts, mountains, tundra and even cities. Peregrines hunt other mid-sized birds such as pigeons, songbirds, waterfowl and shorebirds.
Breeding and Nesting
During breeding season, peregrine falcons nest on tall cliffs or urban towers and skyscrapers. The female typically lays 3-4 eggs which hatch after about a month. The chicks, or eyases, remain in the nest for around 5-7 weeks before fledging and leaving the nest. The parents will continue to provide food for them as they learn to hunt on their own.
Population Decline and Recovery
By the 1960s, peregrine falcon populations had severely declined in many regions due to the effects of pesticides like DDT. Peregrines were even completely extirpated from eastern North America. After DDT was banned, conservation efforts helped peregrine populations slowly recover. They were removed from the U.S. Endangered Species List in 1999 as recovery goals were met.
Today, there are around 2,000-3,000 nesting pairs of peregrines across North America. Though their numbers are healthier, they do still face threats from habitat loss and disturbance of nest sites.
Eagles
Eagles are large birds of prey that sit atop food chains. There are over 60 different species of eagle worldwide. They are members of the broader bird of prey family Accipitridae. Eagles have large, strong beaks and talons for hunting prey, and keen eyesight to spot potential food from afar.
Two species are native to North America: the bald eagle and the golden eagle.
Bald Eagle
The bald eagle (Haliaeetus leucocephalus) is a familiar symbol of wilderness and freedom. These iconic raptors reach wingspans up to 7 feet wide and can weigh up to 14 lbs. They have distinctive brown bodies, bright yellow beaks and talons, and of course, white feathered heads.
Bald eagles live near large bodies of open water like lakes, rivers, reservoirs and coasts where they feed on fish, waterfowl and other small mammals. They construct enormous nests high up in tall trees that they may reuse year after year. Bald eagle numbers dramatically rebounded after the ban of DDT, and they were removed from the U.S. endangered species list in 2007.
Golden Eagle
The golden eagle (Aquila chrysaetos) is a slightly smaller but stockier cousin of the bald eagle. They range in wingspan from 5.5-7.5 feet and weigh 6-13 lbs. Golden eagles have dark brown bodies, golden brown feathers on their head and neck, and lighter gold near their tails.
These powerful hunters live in more open habitats like grasslands, deserts, sagebrush and tundra. They primarily feed on small mammals like rabbits, ground squirrels and prairie dogs but also occasionally target larger prey like foxes, young deer and livestock. Golden eagle numbers remain healthy across their wide Holarctic range.
Peregrine Falcons Attack Eagles
Though eagles are much larger in size, peregrine falcons are agile aerial acrobats that can successfully harass an eagle in flight. Here are some key reasons why the peregrine is the one bird daring enough to attack an eagle:
- Speed – The peregrine is the faster and more agile flier. At stoop speeds over 200 mph, they are the fastest animal on earth. This gives them an advantage maneuvering around the slower moving eagle.
- Defense of nests/territory – Peregrines fiercely defend their nesting areas from intruders. If an eagle ventures too close, the peregrine may harass it to drive it away.
- Smaller turning radius – The peregrine’s smaller size and wingspan allows it to turn tighter circles above an eagle.
- Aerial agility – Peregrines are masters of aerial acrobatics, adept at diving, rolling and swiftly changing directions mid-air.
- Surprise attacks – A peregrine can use the element of surprise and attack an eagle quickly from above or behind before the eagle has a chance to react.
- Maneuverability – Peregrines are extremely maneuverable due to their streamlined bodies and modified talons that enable sudden turns.
There are some YouTube videos that show peregrines aggressively dive bombing and chasing after bald eagles and other birds of comparable size near peregrine nesting sites. The eagles appear startled and struggle to out-maneuver the smaller but quicker peregrines.
Real Life Examples of Peregrines Attacking Eagles
Peregrines Harassing Nesting Bald Eagles
There are documented cases of peregrine falcons continually harassing and attacking nesting bald eagles near their own eyries (nests). One example occurred in British Columbia where peregrines nesting on a transmission tower frequently mobbed and dive bombed a pair of bald eagles at their nearby nest whenever the eagles took flight.
Wildlife researchers speculated the peregrines were acting very territorial and trying to scare the eagles away from the area. While the large eagles didn’t appear too bothered by the smaller falcons, they did have to work harder to avoid the persistent attacks, likely hampering their hunting and feeding efforts.
Young Peregrine Killed by Golden Eagle
In 2006, researchers were shocked to find a young peregrine falcon killed near its nesting cliff in California’s Santa Cruz Mountains. The evidence pointed to a rare attack by a golden eagle as the cause of death. Golden eagle talon marks and feathers were found on the peregrine’s body.
While the speedy peregrines can normally stay out of reach, it seems this particular young bird was caught off guard by the stealthy ambush predator. The golden eagle likely took advantage of local terrain and wind patterns to surprise attack the smaller peregrine from above or behind.
Peregrines Dive Bombing Migrating Eagles
There are quite a few reports of peregrines aggressively dive bombing migrating eagles passing through their fall territories. For instance, during bald eagle migrations along California’s central coast, local peregrines will chase after them to seemingly “escort” the eagles out of the area.
One account describes two peregrines repeatedly harassing a juvenile bald eagle struggling to make headway against strong headwinds. Each time the laboring eagle stopped to rest, the peregrines would swoop down and force it back into flight. Even highly skilled raptors like bald eagles can be caught off guard by the peregrine’s aerial speed and agility.
Eagles Rarely Attack Peregrines
While peregrines are bold enough to pester eagles thanks to their speed and agility, eagles very rarely go after peregrines. Here’s why eagles usually don’t attack them:
- Eagles hunt larger prey – Eagles prefer to target larger birds and mammals. At just over 1 lb, peregrines are too small to make a worthwhile meal.
- Peregrines avoid prolonged exposure – Peregrines only remain within striking distance of an eagle briefly while dive bombing. Their attacks are quick ambushes before swiftly retreating.
- Peregrines nest on cliffs – Their inaccessible nest sites keep peregrine eggs/chicks protected from eagles.
- Peregrines attack in pairs – By mobbing an eagle together, a mated peregrine pair can better drive off intruders.
- Not worth the energy expenditure – The effort required for an eagle to catch a fast-moving peregrine isn’t worth the minimal calories gained.
Essentially, eagles choose not to waste precious energy chasing after pesky peregrines that are low reward and pose little actual threat. It’s more productive for eagles to focus on finding easier prey more calorie-rich prey. Peregrines simply aren’t worth the trouble, despite their daring attitude.
Exception: Larger Eagle Species
Very large eagle species like the Steller’s sea eagle and Philippine eagle are perfectly capable of preying on smaller raptors like peregrines when necessary. Their massive size and strength can overcome even the peregrine’s speed and agility.
For example, there are documented cases of the enormous Steller’s sea eagles occasionally ambushing peregrines at nest sites in Siberia and Kamchatka. At up to 20 lbs, these eagle giants dwarf the 1 lb peregrines and pose a very real predatory threat.
Size Comparison
This table compares the relative sizes of peregrine falcons and several eagle species to illustrate the significant size advantage that very large eagles have over peregrines:
Species | Length (in) | Wingspan (ft) | Weight (lbs) |
---|---|---|---|
Peregrine Falcon | 15-21 | 3-4 | 1-2 |
Bald Eagle | 28-40 | 6-7 | 8-14 |
Golden Eagle | 27-33 | 6-7.5 | 6-13 |
Steller’s Sea Eagle | 33-37 | 7.5-9.5 | 14-20 |
As these comparisons show, bigger eagle species outweigh peregrines by nearly 10 times or more. Their sheer size and power allows them to overtake peregrines under the right circumstances.
Peregrines Occasionally Kill Smaller Raptors
While they are bold enough to mob much larger eagles, peregrines are also known to kill smaller birds of prey, especially during territorial disputes or fights over prey. Some examples include:
- American kestrels
- Merlins
- Sharp-shinned hawks
- Cooper’s hawks
There are rare documented kills of these smaller falcon and hawk species by peregrines defending eyries or competing over shared hunting grounds. So while they may be the featherweight underdogs against eagles, peregrines are also bullies in their own right, capable of taking down lesser raptors.
Conclusion
The peregrine falcon is the only bird daring and agile enough to attack mighty eagles thanks to its blistering speed, aerial acrobatics and fierce defense of nesting territories. Peregrines can successfully harass larger eagles, though outright kills are very rare. Eagles seldom go after adult peregrines since they are too small to be worth the effort. However, very large eagle species are certainly capable predators of peregrines if given the opportunity.
Though bold enough to mob enormous birds 20 times their size, peregrines should still be wary around the largest eagle species that outweigh them by a wide enough margin to make them potential prey. Normally the peregrine holds the advantage against same-sized or moderately larger raptors, but very big eagles are one of the few birds that can turn the tables and override the peregrine’s awesome speed and agility. Nevertheless, the mighty peregrine falcon still stands out as the sole bird audacious enough to attack apex avian predators like full-grown eagles.