Birder’s Notebook: Peregrine Falcon – A conservation success story
Who can resist the majestic sight of a peregrine falcon? Whether perched regally on a nesting cliff, flying or diving with breathtaking speed in pursuit of prey or doing aerobatics for courtship or defense, they are simply aweinspiring birds.
Peregrines, whose name comes from the Latin word for wanderer, travel from Central and South America each spring and breed in our region. According to Travis Booms, Alaska Department of Fish and Game raptor biologist, these falcons are doing very well here, both this year and in general.
Booms found a record number of peregrines during annual raptor surveys this May. Follow up surveys in June found normal numbers of peregrines at traditional nesting cliffs and nesting was in progress.
This was very good news because the unseasonably cold, wet weather in the first half of June took a heavy toll on other raptor species and many nesting attempts failed.
Peregrines nest later than gryfalcons, rough-legged hawks and golden eagles, and thus didn’t yet have vulnerable young during this June’s inclement weather. As a result, so far this season peregrines are having a good year.
In our region, most peregrine breeding sites are along coastal cliffs near seabird colonies. However, Booms reports the species is expanding on the Seward Peninsula and more inland sites are being occupied for nesting.
Peregrine falcons typically return to the same nesting locations year after year. Whether attraction to the site or to the mate keeps pairs together is unknown, but often pair bonds last many years or for life.
Their nest is usually a simple depression on a cliff ledge, formed in whatever surface is on the ledge. No nesting materials are used. However, if another raptor or raven has made a stick nest on the cliff and it is available, peregrines will sometimes occupy it.
In Arctic regions, an average of three eggs are laid, about 48 hours apart. Both parents incubate, but the female spends more time on the nest. The eggs hatch in 33 to 35 days.
Initially the female remains with the young, brooding and tending to their care. Brooding gradually decreases and the female spends less time on the nest ledge, but a parent usually remains on the cliff, on guard nearby. Young make their first flights 39-49 days after hatch.
Soon after their first flights, the young begin to follow their hunting parents, strengthening their wings and begging for food as they fly. One of the many interesting things to watch in the lives of peregrines is aerial transfer of prey from the adults to their young. At first, they meet in the air and the prey is handed off. Later the adult will drop the prey as the young approach and the fledgling must snatch it out of the air. This may be a way of teaching the young to
hunt, or perhaps is just a way for the parent to avoid making contact with hungry, increasingly powerful young.
Peregrines prey mostly upon other birds and were once referred to as “duck hawks.” Birds as large as geese and as small as songbirds are taken. In our region, seabirds are common prey as well as ducks, jaegers, small gulls, shorebirds and ptarmigan.
These falcons are dramatic hunters and are said to be the fastest birds. They watch and wait for opportunity from a vantage point on a cliff or while soaring high on the wing. Once a target is in their sights, they may pursue it at speeds over 60 mph or dive upon it at speeds of up to 200 mph.
A successful chase ends when the peregrine either grabs the prey with its feet or slams into it with its feet, either killing it outright or knocking it to the ground or water below. If the prey is not already dead, the falcon finishes it off with a bite to the neck.
Although peregrines are efficient predators, they sometimes are preyed upon themselves by other large raptors and great horned owls. Peregrine fledglings are especially vulnerable.
Suitable cliff nesting sites are limited, so sometime peregrines share cliffs with other raptors and ravens. In these cases they seem to have an uneasy relationship with their neighbors and territorial disputes sometimes erupt, occasionally resulting in death.
Historically, peregrine falcons were one of the most widespread birds on earth. However, for a time this distinction was threatened. In the 1950s and 1960s peregrine populations declined precipitously as a result of eggshell thinning from widespread use of DDT. Peregrines disappeared from much of their former breeding range in many parts of the world. Other raptors suffered similar declines, but the charismatic and popular peregrine falcon became the poster child in the fight to ban DDT, which finally was accomplished in 1972.
Peregrine populations were so diminished that it took large-scale captive breeding programs to restore the birds to their former range in North America. These falcons were always highly valued for falconry, so captive rearing techniques were already well established and the recovery effort was a huge success.
Over the decades, peregrines have reoccupied their former range and again fly the skies above all continents except Antarctica. They nest in a remarkable variety of habitats, from Arctic coastal cliffs to skyscrapers of the world’s largest cities where they dine on pigeons.
The future looks promising for these swift and adaptable falcons in our region and around the world.