Peregrine falcons are fascinating birds of prey that can be found on every continent except Antarctica. They are best known for their incredible speed and aerial acrobatics. Peregrine falcons mate and lay eggs in the springtime each year. The exact timing of their breeding season varies across their global range based on local conditions and food availability. Generally speaking, courtship and mating occurs in March through May in most regions.
Courtship and Mating
Peregrine falcons reach sexual maturity and begin seeking mates at around 2 years old. In preparation for the breeding season, mature adults will return to nesting sites from their wintering grounds in late February or March. COURTSHIP begins with spectacular aerial displays as pairs or groups fly high in the sky and then dive steeply. The male will present prey items to the female as an offering. If she accepts, it signifies their bond and she allows him to mate with her. Copulation happens on cliff ledges or previous nest sites. The male mounts the female’s back and holds her nape in his beak to steady her. Actual mating only lasts a few seconds. Although peregrines are mostly monogamous, a male may mate with several females in a season before settling with one mate.
Spring Migration and Courtship Displays
One intriguing aspect of the peregrine falcon reproductive cycle is timing their spring migration to coincide with courtship. The falcons that migrated south for the winter must make their way back to traditional nesting sites in March and April. This journey is thought to help initiate hormonal changes related to breeding. The males especially put on spectacular aerial displays during migration to attract and bond with females. Groups of peregrines meet up at preferred courting spots on the migration routes. They dazzle each other with breathtaking dives called stoops where they tuck in their wings and free-fall at speeds over 200 mph before pulling up sharply. The coordinated group displays may help judge a potential mate’s flying skills.
Egg Laying and Incubation
Once a monogamous pair bond is formed, the female is ready to lay eggs within a week or two. She scrapes out a shallow nest depression called a scrape on a ledge or cliff crevice. Peregrine falcons do not build nests out of sticks, grass or feathers. They simply use a bare depression in gravel or dirt on a rocky outcrop. The female lays between 3 to 4 eggs that are whitish or cream-colored with brown blotches. The eggs measure about 2 inches long. She lays one egg every 1 to 2 days until the clutch is complete. Then both parents share sitting on the eggs to keep them warm and protected. Incubation lasts about 33 days before hatching.
Ideal Nest Sites
Peregrines nest on tall cliffs and urban buildings rather than trees. High elevations allow them to easily take flight and provide panoramic hunting views. Ideal nest sites include:
- Cliffs up to 2,000 feet high
- Ledges at least 4 inches deep and 12 inches wide
- Protected overhangs or small caves
- Tall urban structures – skyscrapers, bridges, smokestacks
The parents will aggressively defend the nest site throughout incubation and the rearing of chicks. Some pairs may use the same nesting crevice for many years.
Incubation Responsibilities
Both the male and female peregrine take turns incubating the eggs. They share duties equally with the female taking the night shift and the male during the day. Incubation begins when the first egg is laid, so the eggs hatch asynchronously over several days. The eggs must be kept at temperatures between 85-92°F for proper embryonic development. To maintain optimal egg temperature, the parent sits directly on the eggs and rotates them periodically. If the eggs are left unattended, they will quickly chill and the embryos could die within a few hours.
Hatching and Raising Chicks
Peregrine falcon eggs begin hatching after 32 to 35 days of incubation. The white eggshells break open and wet, partially feathered eyases emerge. Newly hatched chicks weigh around 20 grams and are totally helpless. Their eyes are closed and they can’t regulate body temperature or lift their heads. Both parents feed and brood the chicks to keep them warm and safe. For the first 10 days, the female stays at the nest almost full time while the male hunts. He passes prey to the female who tears it into small bits to feed the chicks directly. As they grow bigger and stronger, the eyases are able to eat larger pieces.
Growth and Development
Peregrine falcon chicks develop rapidly under the constant care of their parents. Here is a timeline of early growth and milestones:
Age | Developmental Changes |
---|---|
5 days | Open their eyes |
10 days | Covered in white down |
18 days | Can lift head and walk around nest |
21 days | Dark wing feathers emerge |
Within 6 weeks, the chicks are nearly adult size and ready to take their first flights from the nest ledge. They will continue hunting with their parents for 2-10 more weeks to learn flying and hunting skills before dispersing from the natal territory.
Survival Threats
Peregrine falcon eggs and chicks face many natural threats during the breeding season including:
- Predators – ravens, owls, eagles
- Weather – storms, flooding, temperature extremes
- Food shortage – insufficient prey provisioning
- Human disturbance – rock climbing, infrastructure on cliffs
Adults aggressively defend the nest from intruders. Also, remote high cliff sites offer more protection compared to man-made structures. Fledging success averages 1.5 chicks per nest but mortality is still high in the first year of life.
Diet and Hunting During Breeding
Peregrine falcons are deadly hunters that catch avian prey in mid-flight. Their diet shifts to smaller, more abundant birds in the spring to adequately provision growing chicks. Hunting and feeding demands are extremely high during breeding. The female especially depends on the male to deliver enough prey while she incubates eggs and broods hatchlings. A mated pair and their chicks can consume well over 1,000 birds during a single breeding season!
Preferred Prey
Peregrines will hunt any species but prefer medium-sized birds such as:
Habitat | Favored Prey Examples |
---|---|
Coasts | Seabirds – ducks, gulls, shorebirds |
Wetlands | Herons, grebes, coots |
Cities | Pigeons, doves, starlings |
Grasslands | Meadowlarks, blackbirds, quail |
During breeding, peregrines switch their diet to the most common small bird species near the nest, rather than migratory waterfowl or gamebirds.
Hunting Style
Peregrines are specialized for hunting other birds in flight. They spot prey from high perches and stoop downwards at speeds over 200 mph to strike in mid-air with their talons. The force of impact stuns or kills the prey immediately on contact. If not, the falcon bites the neck of prey to ensure a swift kill. Then they carry prey back to the nest with their strong grasping feet. The female especially needs a constant supply of fresh meat and bones to produce eggs and feed chicks.
Geographic Variation in Breeding
Peregrine falcons are found on every continent except Antarctica and successfully breed in diverse habitats from tundra to tropics. Their breeding activities are finely tuned to the local climate and food resources. Here are some examples of variation seen across different regions:
Arctic
- Begin courtship in April
- Nest on cliffs and rocky tundra outcrops
- Hatch chicks in June
- Prey on small tundra birds and shorebirds
Temperate Coasts
- Court in March, nest in April
- Use coastal cliffs and city bridges
- Chicks hatch in late May
- Eat ducks, grebes, gulls, pigeons
Southern Deserts
- October through March breeding season
- Limited nest sites on cliffs and buildings
- Chicks reared in winter months
- Hunt doves, swifts, quail year-round
Their versatility allows peregrines to produce young across diverse environments worldwide.
Conservation and Recovery
Pollution and habitat loss caused alarming declines of peregrine falcons in the mid-20th century. DDT pesticide biomagnified up the food chain and thinned their eggshells. As few as 320 pairs were left in North America by 1975. Captive breeding and release programs helped peregrine populations recover in many regions. Their adaptability also allowed them to flourish in cities. Today, over 2,000 pairs nest across the U.S. and Canada again. Ongoing monitoring and protection of breeding sites is key for their continued success.
Early Conservation Efforts
With peregrine falcon numbers rapidly dwindling in the 1960s, concerted conservation efforts were launched:
- Banned DDT in Canada (1970) and the U.S. (1972)
- Restricted access near nest sites
- Artificial incubation and rearing in captivity
- Captive breeding at The Peregrine Fund’s facility
- Hacking – controlled release of captive-bred juveniles
These initiatives helped peregrine populations start to recover in the 1980s and 1990s as reproductive success improved.
Monitoring and Current Status
Biologists track peregrine reproduction and health to identify ongoing threats. Nesting success and population increases show their resiliency. However, habitat loss and emerging contaminants remain concerns. Their current status is:
- Removed from U.S. Endangered Species list in 1999
- Still listed as threatened/endangered in some western states
- Designated a species of Least Concern globally
- Population estimated at 100,000 to 499,000 worldwide
Targeted conservation action pulled peregrine falcons back from the brink and numbers continue to rise. But maintaining clean, undisturbed breeding sites remains important for their reproduction and survival.
Conclusion
Peregrine falcons are magnificent avian predators that breed in the springtime across temperate, Arctic, and some tropical regions. Their courtship flights, nesting habits, and hunting prowess are all fine-tuned to allow successful reproduction. The timing of migration, egg-laying, and chick-rearing varies around the world based on climate and food availability. Peregrine populations can thrive when provided with undisturbed nesting cliffs and ample prey. Targeted conservation efforts in the late 20th century helped restore their numbers after declines from pesticide poisoning. Ongoing monitoring and protection are needed to allow peregrine falcons to continue their incredible aerial feats and raise young each spring.