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Peregrine Falcon Information

The peregrine falcon (Falco peregrinus) is a very distinctive bird of prey, with slate blue upper parts and cream-coloured under parts with black bars, and a prominent "moustache" mark on the side of the face. Young birds are brown above and buff underneath, with streaks rather than bars. Adult birds range from 30 to 50 cm (15 to 20 inches) in length, with a wingspan of 95 to 115 cm (roughly 36 to 45 inches). They weigh between 600 and 1300 grams (21 to 46 ounces), females being considerably larger than males.

The fastest creature on earth

They are powerful, streamlined birds, capable of soaring to heights of several hundred feet. When a peregrine falcon swoops it has been recorded as the fastest animal on earth reaching speeds in excess of 200 miles per hour (322 km/h). They are expert hunters feeding on a variety of birds, all of which are caught in flight. However, they do seem to be particularly partial to pigeons. The peregrine is anatomically specialized for hunting by direct pursuit in open areas. The prey often tries to escape by gaining altitude but the peregrine uses its speed to stay above the prey, and then dives, killing the prey striking it with clenched talons and killing by impact. In addition to speed the peregrine may use the element of surprise - swooping from the direction of the sun or suddenly appearing from behind a cliff, or around the corner of a tall building.

Range

While peregrines are rare, they are remarkably widespread. They have a more extensive natural global range than any other bird. Peregrines can be found on every continent except Antarctica.

Almost lost

While the peregrine, at least in this country, generally seems to live in harmony with man, largely due to man now realising what a magnificent and precious creature the peregrine is, this has not always been the case and the treatment they have been afforded has, at times, been bizarre.

It is estimated that in the 1930s we had a national population of 700 pairs of birds. During the Second World War this figure fell to about 100 pairs when, being considered "an enemy" of the homing pigeons that were in military use, about 600 pairs of birds, mostly in southern Britain, were shot. After the war peregrine numbers began to increase and they became a protected species given special cover by the 1954 Protection of Birds Act (racing pigeon enthusiasts, of course, objected!!).

In the 1950s peregrine populations were decimated all over the world by organochlorine pesticide poisoning (such as from DDT). It was noted that there had been a severe decline in this country since 1956 and that by 1963 there were just 360 pairs in Britain.

A survey of peregrines in 1961 and 1962 carried out under the leadership of Derek Radcliffe, a naturalist, for the British Trust for Ornithology found that there had indeed been a sharp decline in the peregrine population. It was found that the organochlorines were accumulating in the falcons and causing their eggs to break prematurely as the shells were thinner than they had been before the use of these pesticides began. The scientific paper that was published in 1967 as a result of the survey led to the phasing out of DDT and the populations of peregrine and other falcons began to rise again. It is ironic, although the specifics are not known, that the peregrine survey and the findings as to the detriment to the environment of DDT may not only have benefited the falcon community but also averted human health problems by stopping DDT getting into the human food chain.

Recovery

Following the restriction of organochlorines and enhanced protection efforts, there are now over 1,200 pairs, though numbers have not yet recovered in south-east England and east Yorkshire, while in north Scotland there have been declines over the last decade. Persecution, environmental pollutants and, possibly, declines in the abundance of their prey may be restricting the peregrine population.

Home

When nesting peregrines choose a site which is an isolated protected spot near good hunting grounds. Most of the time this is a cliff or rocky outcrop. Most nests, regardless of where they are located, consist simply of a shallow depression scraped out by the adults; no nest materials are added. The size of a breeding territory varies greatly among individual Peregrines. In some cases nests may be within less than one kilometre of each other, while in other places a pair will defend a territory with a radius of 20 kilometres or more. While several factors may be involved, it appears that food availability is the primary limitation on nesting density. A pair of birds will generally treat their nest as the centre of their territory which they will fiercely defend and will usually return to the same nest year after year, although they may have one or two alternative nest sites within the same area.

In recent decades, peregrines have started to live in towns and cities on an increasingly regular basis, using tall buildings and high bridges as nesting sites. To a peregrine, a sheltered ledge high on an office tower is much like a towering cliff.

A mate for life

Mating begins a lifelong pairing, but if one of the pair dies the surviving bird will take a new partner. While they may be mates for life, they are not equals. In a typical nest, the female is the dominant partner.

Breeding

Females lay two to five eggs in the "scrape" or nesting site, which is usually just a shallow depression. Eggs are incubated for 4 to 5 weeks, mainly by the female, while the male hunts for food. The young are able to fly at about 35-40 days after hatching, but remain dependent on the adults for several weeks after they leave the nest. The young birds may stay together for a short time after they become independent of the adults, but they will not normally have any further contact with their parents for the rest of their lives. Peregrines rarely breed before three years of age. The average life span is 13 to 17 years but individuals have been known to live longer.