Thursday, August 6, 2009

Fastest Bird in the World: Peregrine Falcon

Adult Peregrine Falcon in Flight. Photo by Doug Brown.

Fact or Fiction? Various accounts report top speeds ranging between 100 and 250 miles per hour for the Peregrine Falcon. Most, however, agree that in a stoop (when the bird is diving on prey) that it is indeed the fastest on our planet. Recent technology enabled a team of scientists, lead by falconer and researcher, Ken Franklin, to attach a speed monitor similar to those used in sky diving to his falconry bird, Frightful. National Geographic filmed her remarkable descent as Frightful adjusted her body’s position to become as streamlined as possible once the lure (a leather pouch designed to look like a bird) was released. Although some might argue that since the bird was lifted aloft via aircraft, possibly skewing the results, Frightful reached a top speed of 242 miles per hour while diving on a lure, impressive in the extreme.

Extreme might be one of the adjectives that best describes this remarkable species. Throughout history, humans have been held spellbound by the aerial acrobatics of the peregrine and other large falcons. Few other North American species have been as highly regarded and romanticized in the second half of the 20th century. The peregrine is among the most studied of all wild birds, with over 2,000 scientific publications. The falcon has been eulogized in numerous books and poems, and appears in a wide variety of art dating back several centuries. Its daredevil acrobatics undoubtedly inspired the sport of falconry, where participants may witness these remarkable flights close at hand. During the heyday of falconry in the Middle Ages, the peregrine was the most prized of hunting hawks and reserved for the pleasure of the aristocracy. Severe penalties were incurred for harming a wild falcon or robbing her eyrie (nest).

Revered to reviled: After the introduction of firearms, and conversion of land to agriculture, the sport of falconry declined, and peregrines came to be regarded as vermin, relentlessly persecuted by gamekeepers, hunters, egg-collectors, skin collectors, pigeon fanciers, and others. From the 18th century until the mid 1900s, this attitude persisted and humans destroyed many thousands of peregrines, eggs, and young worldwide. It should be noted that this attitude extended to all raptor species, not just falcons. Yet, falcon populations were remarkably resilient to hunting pressure. One estimate reported a decline of only 10-18% in occupied territories by the 1930s and it was impossible to determine the if they were permanently deserted.

By World War II, the peregrine was viewed as a menace to the all important carrier pigeons, and the British Air Ministry undertook a campaign to eradicate the falcons in the south of England. The control measures resulted in the systematic destruction of 100 or more eyries and shooting about 600 falcons each year. However, within 10 years after the persecution ended, falcon pairs were again present at 80% of those eyries. However, a far greater threat to its survival loomed on the horizon: pesticides.

Vanished: In the mid 1960s, researchers and falconers realized that Peregrine Falcon populations were in deep trouble in North America. A population crash had been occurring for the past 10-15 years, on a parallel with declines of the species in Europe. Except for one eyrie that continued to be occupied until the 1980s, peregrines had vanished east of the Mississippi River. They probably also disappeared from most eyries in the Rocky Mountains at about the same time, although it was not until the 1970s that adequate surveys took place and verified the suspicions of scientists. By 1980, no active eyries could be found in Idaho, Montana, or Wyoming. Suddenly, it seemed as if only 15-20% of the former total population in the lower 48 United States survived.
DDT (dichloro-diphenyl-trichloroethane) was considered to be a safe and effective insecticide in the 1940s and 1950s. It was used as an agricultural insecticide, and to combat lice and mosquitos responsible for the spread of human diseases such as typhus, and malaria. There were no known significant adverse effects to either animal or human health, that is, until Peregrine Falcon populations, along with other birds such as the Bald Eagle and Osprey crashed.
When DDT use was widespread, daily doses of the chemical accumulated in the fatty tissue of the peregrine. The stored chemicals acted to "block" the movement of calcium during eggshell formation causing the shells to be "thin." Peregrine falcon eggs broke and embryos died at an alarming rate. The peregrine became the cause célèbre for the fledgling environmental movement, lead by the publication of Rachel Carson’s landmark book, Silent Spring.

By 1970, the peregrine was federally protected in the United States, and the chemical culprits were banned in North America by 1972. Peregrines were have since made a strong recovery, thanks in large part to extensive captive breeding and release programs implemented by The Peregrine Fund of Boise, Idaho. They were officially de-listed on August 20, 1999, although they remain a state-listed species in New Mexico.

Lessons learned from the plight of the peregrine have worked their way into science curriculums throughout the U.S. Most third and fourth grade students understand what the words “endangered” and “extinct” mean. We are extremely fortunate that falcon watching of this charismatic bird alerted the world to a problem in time for there to be a resolution. Will we be as lucky in the future?

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