Quick Answer
Peregrine falcons do build nests, which are known as eyries or scrapes. They do not build traditional nests out of twigs, grass, and mud, but rather scrape out a shallow depression on cliff edges or tall buildings to use as a nest. The nests provide a place for the female peregrine to lay eggs and raise young.
Peregrine Falcon Overview
The peregrine falcon (Falco peregrinus) is a powerful bird of prey found on every continent except Antarctica. Some key facts about peregrine falcons:
- They are renowned for their speed, reaching over 200 mph during hunting dives.
- They mainly prey on other birds such as pigeons, ducks, and songbirds.
- Peregrines are about 15-20 inches long with a wingspan around 3 to 4 feet.
- Their lifespan is up to 15 years in the wild.
- Peregrine falcons experienced significant population declines in the mid 20th century due to pesticide use, but have rebounded thanks to conservation efforts.
- While once endangered, they are now classified as a species of Least Concern.
Peregrine falcons are found on every continent except Antarctica. They live in a variety of habitats including coasts, mountains, deserts, and wetlands. Peregrines typically nest on tall cliffs overlooking rivers, lakes, or marshes where prey is abundant. They also readily adapt to urban environments and often nest on tall buildings and bridges.
Do Peregrines Build Nests?
Yes, peregrine falcons create nests called scrapes or eyries in which to lay eggs and raise young. However, they do not build nests out of materials like twigs, grass, and mud the way many bird species do.
Instead, they simply scrape a shallow depression out of a substrate such as loose gravel on a cliff ledge or soil on a building rooftop. The nest may be lined with some pebbles, grass, debris, or feathers, but little nest construction or bringing of materials occurs. Peregrines rely on the pre-existing cliff ledge or rooftop surface to provide a suitable nesting location.
Cliff Nest Sites
In natural settings, peregrine falcons overwhelmingly nest on tall cliff faces overlooking rivers, coasts, or wetlands. Their nests are called eyries when located on cliffs. Ideal cliff eyries provide the peregrines with protection from above and a wide vista for spotting prey.
Peregrine falcons prefer cliffs around 100-200 feet tall, though they may nest on higher or lower cliffs as well. The ledges they select are usually bare of vegetation and offer a wide, flat space for the nest. Ideal eyries face south or southwest to provide shelter from cold northerly winds.
Using their talons, the peregrines scrape out a shallow depression around 8-12 inches across and 2-3 inches deep on the cliff ledge. They may line it with small rocks, debris, food remains, and feathers. This simple scrape nest provides a place for the female to lay eggs, incubate them, and shelter the chicks after they hatch.
The pair will often return to the same cliff eyrie year after year. Some active nest sites may be used for a decade or longer by successive generations of falcons.
Urban Nest Sites
As peregrine falcons adapted to urban environments in the second half of the 20th century, they began regularly nesting on tall buildings, smokestacks, bridges, and other man-made structures. Their nests on buildings are still called scrapes.
Peregrines seem to prefer nest sites at least 50-100 feet high on urban structures. As with natural cliff eyries, they look for ledges and outcrops that provide an unobstructed view and ample room for the nest. Common nest locations include under bridges, inside gravel beds on rooftops, and on narrow ledges on tall buildings.
The falcons may start from scratch or take over old nests built by other raptors like red-tailed hawks. The peregrines will simply scrape out the existing nest materials down the bare surface and reuse the site.
Urban peregrine pairs frequently reuse the same building or bridge nest site for many years. As the eyries are undisturbed by weather and erosion, they may last longer than natural cliff nests.
Nesting Behavior
Peregrine falcon nesting behavior involves scraping the nesting depression, defending the territory, mating, incubating the eggs, and raising the young.
Scraping the Nest
Starting 2-4 weeks before the first egg is laid, the female begins spending more time at the nest cliff or structure. She scrapes out a shallow depression in the gravel or soil using her beak and talons. The male may assist in nest scraping as well. This simple bare scrape is the peregrine’s nest.
Over time, the female may line the nest with some small rocks, grass, sticks, litter, prey feathers, or other debris. But peregrines do not carry in substantial nesting material the way many birds do. The eyrie remains a relatively sparse and shallow depression relying on the underlying ledge surface.
Territorial Defense
Peregrine falcons are highly territorial during the breeding season. The male has a strong instinct to defend the cliff eyrie or urban nest structure against intruders. He will actively chase away intruding peregrines or other species that venture near the nest.
Both the male and female may engage in dramatic aerial battles with peregrines or raptors like bald eagles that pose a threat to their territory. They use vocalizations, stoops, physical attacks, and their sheer aggression to drive intruders away. This helps ensure that the nest area remains free of threats.
Mating and Egg Laying
Once the scrape nest is prepared, the female is ready for mating and egg laying. Peregrine falcons mate repeatedly starting up to two months before the first eggs are laid.
The female then lays a clutch of 3-4 eggs (and rarely up to 6) at two day intervals. The eggs are creamy or rusty reddish-brown with darker blotches. She begins incubating the eggs as soon as the first one is laid, keeping them warm with her brood patch.
The male regularly brings food to the female while she incubates. After 33-35 days of incubation, the eggs begin hatching over several days.
Raising the Young
Baby peregrines are covered in white down and rely completely on their parents for food, warmth, and protection. For the first 2-3 weeks, the female broods the chicks while the male hunts and brings food to the nest. After that, the female also leaves the nest to hunt while the chicks shelter together.
The parents tear up prey into smaller pieces to feed the growing chicks. Around 35-42 days after hatching, the chicks are fully feathered and ready to start flying. They spend the next few weeks perfecting their flying and hunting skills under their parents’ supervision.
Around 6-10 weeks after fledging, the young peregrines leave the parents’ territory to find their own territories and mates. The parents may start preparing for a second brood around this time.
Significance of Nest Sites
The nest sites peregrine falcons choose and defend are critical for:
- Providing a safe place to lay and incubate eggs
- Sheltering the chicks when they are most vulnerable
- Giving protection from weather and predators
- Offering easy access to abundant food sources
Nest sites with ideal protection, space, views, and food availability allow the peregrines to successfully hatch and raise chicks each year. Without secure nesting spots, their breeding success would be greatly reduced. The fact that peregrines are willing to reuse nest sites and eyries for many years indicates how important suitable nesting locations are.
Cliff eyries and urban nest sites are essential centers of breeding activity for peregrine falcons. Their nesting habits may be simple, but the scrapes provide everything this avian predator needs to perpetuate the next generation.
Frequently Asked Questions
What materials do peregrine falcons use to build nests?
Peregrine falcons do not build substantial nest structures. They simply scrape shallow depressions on cliff ledges or urban structures to use as nests. They may line the scrapes sparsely with pebbles, debris, grass, and feathers but do not carry in nesting material like twigs.
How high do peregrines build nests?
On natural cliffs, peregrines usually nest 100-200 feet high, but may nest on higher or lower cliffs too. On urban structures they prefer nest sites at least 50-100 feet high such as rooftops, bridges, and tall buildings.
Do peregrines reuse nest sites?
Yes, peregrine falcons show strong fidelity to nest sites and will reuse them for many years. Some cliff eyries and urban nest structures are occupied by successive generations for a decade or longer.
How many eggs does a peregrine lay?
A typical peregrine falcon clutch contains 3-4 eggs. The female may lay up to 6 on rare occasions. She begins incubating as soon as the first egg is laid. After a 33-35 day incubation period, the eggs hatch over several days.
How long do the young peregrines stay in the nest?
The chicks fledge (make their first flight) around 35-42 days after hatching. But they continue to be fed and trained by the parents for another 6-10 weeks before dispersing from their parents’ territory.
Conclusion
In conclusion, peregrine falcons create simple scrape nests on cliff edges and urban structures in which to breed. They do not construct complex nests out of materials, but instead scrape shallow depressions to use as eyries or urban nest sites. These sites are critical for protecting the eggs, sheltering chicks, and providing easy access to food. Peregrine falcons demonstrate strong fidelity to nest sites and may reuse them for many years. Their scraping nesting behavior is a key adaptation that has allowed them to thrive and recover populations after endangerment. The peregrine’s ability to make do with basic nesting requirements shows its resilience as a species.