The peregrine falcon is often called the fastest animal on Earth, reaching around 200 miles per hour or more when it dives on prey. Surviving that is not one trick but a whole body redesigned for speed, from its bones to its eyes to its lungs. The hardest moment is not the plunge itself but the sudden pullout at the bottom.
What Happens During a Peregrine’s Dive
A dive, or stoop, begins with the bird climbing to a great height. It then folds its wings and drops steeply toward a bird flying below.1Wikipedia. Peregrine falcon At the end it strikes its prey in mid-air, often hitting one wing so it doesn’t hurt itself on impact.2Wikipedia. Peregrine falcon
Falcons climb first because level, flapping flight tops out well below diving speeds. The bird spends its own energy on the climb and lets gravity supply the speed on the way down. Height is stored energy, so the higher the starting point, the more speed gravity can add. That is why the very fastest dives begin at great altitude.
The famous 200 mph figure comes mostly from trained falcons diving from great heights, not from typical wild hunts. Some sources quote up to 240 mph, which is why the numbers vary.
Radar tracking of wild dives found average speeds of about 25 meters per second, roughly 55 mph, over dives lasting 40 to 110 seconds.3Ibis. Radar observations of the stoop of the Peregrine Falcon Falco peregrinus and the Goshawk Accipiter gentilis The fastest 10-second stretches reached about 31 to 39 meters per second, around 70 to 87 mph.4Ibis. Radar observations of the stoop of the Peregrine Falcon Falco peregrinus and the Goshawk Accipiter gentilis These birds were diving well below the top speed physics says they could reach, and a moderate speed may let the falcon aim more precisely.5Ibis. Radar observations of the stoop of the Peregrine Falcon Falco peregrinus and the Goshawk Accipiter gentilis
A faster dive is not automatically a better one. The faster the falcon goes, the less time it has to correct its aim, and the wider its turning circle becomes.
Computer simulations suggest a slow, low dive works best against prey flying in a straight line, hitting at about 35 to 45 meters per second.6PubMed Central. Physics-based simulations of aerial attacks by peregrine falcons reveal that stooping at high speed maximizes catch success against agile prey Against prey that dodges sharply, the best results came from dives starting around 1,500 meters up and hitting at over 100 meters per second, about 220 mph.7PubMed Central. Physics-based simulations of aerial attacks by peregrine falcons reveal that stooping at high speed maximizes catch success against agile prey So a falcon may hold back against an easy target and save the extreme dive for agile birds.
Bones Built for the Pullout
When a falcon pulls out of a dive, it is pressed by a force many times its own body weight, the same kind of force fighter pilots feel. Tracking of a falcon in a controlled setting, along with predictions for high-speed pullouts, points to very large loads during this turn.8AIAA Journal. Peregrine Falcon’s Dive: Pullout Maneuver and Flight Control Through Wing Morphing
The pullout is harder than the plunge. During the steep drop the falcon is moving fast but in a nearly straight line, so the force on its body is modest. When it bends that path upward, the wings must produce a large sideways force to turn the whole body, and that is where the load spikes. The faster the bird is moving, the more punishing a tight turn becomes.
Compared with three related bird species, peregrines had heavier arm bones and shoulder bones for their size.9PubMed. The peregrine falcon’s rapid dive: on the adaptedness of the arm skeleton and shoulder girdle Their upper wing bone was shaped to resist bending best of all.10PubMed. The peregrine falcon’s rapid dive: on the adaptedness of the arm skeleton and shoulder girdle The wing bones and breastbone were the most mineral-dense, and the arm and shoulder bones were the strongest.11PubMed. The peregrine falcon’s rapid dive: on the adaptedness of the arm skeleton and shoulder girdle
Most birds keep their bones light to save weight in flight. The peregrine trades some of that lightness for strength where it matters, and the extra mass is focused in the wings and shoulders rather than spread everywhere.
The wings help too. Spreading the outer wing during a pullout creates swirling air that adds lift, much like delta-winged combat jets.12AIAA Journal. Peregrine Falcon’s Dive: Pullout Maneuver and Flight Control Through Wing Morphing That extra lift lets the bird turn sharply without needing larger, heavier wings.
Eyes That Work at Diving Speed
Falcons have a thin, see-through third eyelid that sweeps across the eye.13Bay Nature. Q: I’ve heard that hawks have an extra eyelid or membrane that protects their eyes while they hunt. Is that true? Do other animals have extra eyelids? It keeps the eyes from drying out in the rushing air of a dive.14Bay Nature. Q: I’ve heard that hawks have an extra eyelid or membrane that protects their eyes while they hunt. Is that true? Do other animals have extra eyelids?
The third eyelid slides across the eye from the inner corner toward the outer, rather than dropping down like our eyelids. Because it is thin and clear, the bird keeps a blurred but usable view while the eye is covered. Besides blocking wind, it spreads moisture across the surface of the eye, a bit like a windshield wiper.
A peregrine can tell flickering light apart at 129 flashes per second or more.15Journal of Experimental Biology. How fast can raptors see? A slower-flying Harris’s hawk manages only about 81, and people usually around 60. Each moment is captured in finer slices, so fast-moving prey looks smoother and less blurred to a falcon. That matters when closing in on a bird that can twist suddenly, because small changes in its path show up sooner.
A falcon’s sharpest vision points forward and about 45 degrees to the side, not straight ahead.16PubMed. The deep fovea, sideways vision and spiral flight paths in raptors Each eye actually has two high-detail areas. The deeper one points to the side and is likely sharper, while the shallower one points closer to straight ahead and may help near the end of the dive.
To keep that sharp spot on its prey with its head held straight, a falcon flies a spiral-shaped curved path.17PubMed. Curved flight paths and sideways vision in peregrine falcons (Falco peregrinus) Wild peregrines approached small birds this way from as far as 1,500 meters.18PubMed. Curved flight paths and sideways vision in peregrine falcons (Falco peregrinus) Looking straight at the prey would mean turning the head away from the body’s line, which would add drag and slow the dive. Instead the falcon keeps its head aligned with its body and lets the curve of its path hold the prey in the sideways sharp spot.
Wings and Airflow That Keep It Stable
In a partly tucked dive the falcon’s wings form an M-shape when seen from above.19PubMed Central. Vortices enable the complex aerobatics of peregrine falcons The wings are swept back at the wrist and forward again at the tips. The angled front edge of each wing sets up airflow running sideways along the wing as well as backward over it, which steers air inward and helps it stay attached instead of breaking away.20PubMed Central. Vortices enable the complex aerobatics of peregrine falcons Sideways airflow of roughly 8 to 15 percent of the bird’s speed re-energizes the air layer over the wing.21PubMed Central. Vortices enable the complex aerobatics of peregrine falcons
Air peeling away from the wing is a problem because lift drops suddenly and drag climbs. At the high speeds and sharp angles of a dive, a wing with no way to hold the airflow could lose control. Keeping the air attached lets the falcon keep steering with small, smooth wing changes.
Normally, making more lift creates more drag and would slow a bird down a lot.22PubMed Central. Vortices enable the complex aerobatics of peregrine falcons But pairs of swirling air currents made by the falcon’s wings reduce that drag.23PubMed Central. Vortices enable the complex aerobatics of peregrine falcons The falcon can steer hard during a dive while keeping its speed.
The bird also changes its shape as the dive goes on. Fully tucked wings give a teardrop for maximum speed, and partly opened wings give control and steering. Spreading the outer wing is how it brakes and turns at the bottom.
Breathing and Heartbeat at Full Speed
Birds have stiff lungs fixed to the ribs, with soft air sacs that act like bellows.24Ostrich. Functional morphology of the avian respiratory system, the lung–air sac system: efficiency built on complexity Air flows in one direction through the lungs all the time, not in and out as in ours.25Ostrich. Functional morphology of the avian respiratory system, the lung–air sac system: efficiency built on complexity
Air sacs at the front and back of the body push air through the lungs and hold it in reserve. Fresh air passes through the lung on the way in, and used air passes through on the way out. It takes two breath cycles for a single bit of air to make the full trip.
Because the lung doesn’t have to expand and shrink with each breath, its wall can be very thin and packed with tiny air passages and blood vessels where oxygen moves into the blood. The air sacs do the bellows work, leaving the lung free to exchange gas.
A peregrine’s heart can beat 600 to 900 times a minute.26Meigs Point Nature Center. Peregrine Falcon – Meigs Point Nature Center, Madison, CT Blood carries oxygen around the body very quickly.27Meigs Point Nature Center. Peregrine Falcon – Meigs Point Nature Center, Madison, CT
Striking Prey Without Getting Hurt
Hitting a wing rather than the body lets the falcon knock prey out of the air without a full collision.28Wikipedia. Peregrine falcon A wing is light and sticks out from the body, so a strike there knocks the prey off course without the falcon plowing into solid body mass.
Many raptors seize prey in their talons and hold on. A falcon often hits first and grabs afterward, using its toes like a fist to knock the prey rather than to hold on. It then has to catch up with the stunned bird before it hits the ground or recovers.
Falcons have a sharp, tooth-like notch on the beak.29PubMed Central. Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique They kill by quickly biting the neck and breaking it.30PubMed Central. Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique The tooth fits between the neck bones, so a quick bite can separate them. That means they don’t need large talons to hold struggling prey.31PubMed Central. Predatory Functional Morphology in Raptors: Interdigital Variation in Talon Size Is Related to Prey Restraint and Immobilisation Technique A fast kill ends the struggle and cuts the chance of injury to the falcon, which often plucks the neck feathers first.
How Young Falcons Learn to Dive
Young peregrines must quickly learn speed and accuracy to survive.32Alberta Institute For Wildlife Conservation. Peregrine Falcon Hunting Strategy The body plan is inherited, but judging a prey’s speed and direction takes experience. A fledgling must learn how to time its dive, when to pull out, and how to judge a target’s likely moves.
Practice starts with chasing siblings and parents in the air. Parents may drop prey for the young to catch. Adults keep feeding young falcons for a while after they leave the nest, so the young can practice without starving. Over weeks, they shift from begging for food to catching their own. Mistakes at high speed are costly, and many young falcons die in their first year while learning.
You can watch this yourself. Many cities have nesting pairs on tall buildings and bridges, and some have public webcams during nesting season. Spring and early summer are busiest for flight practice.