Seasons of the Tallgrass Prairie by Paul A. Johnsgard

Author:Paul A. Johnsgard [Johnsgard, Paul A.]
Language: eng
Format: epub
Tags: NAT024000 Nature / Essays
ISBN: 9780803256972
Publisher: UNP - Bison Books
Published: 2014-09-16T04:00:00+00:00

13

Nebraska’s City-Dwelling Peregrines

During the 1930s and 1940s there were about 500 pairs of peregrines in the United States, including about 210 active nests in the eastern states and 250–350 nests in the western United States. Additionally, the arctic peregrine, a tundra-nesting race, consisted of perhaps 150 pairs that nested in high latitudes from Alaska to Greenland. Over all of their range the birds typically nested on steep cliff sides, and because of this need for tall-cliff nesting sites, there are no firm historical nest records for Nebraska, although some evidence exists for possible breeding having occurred near Fort Robinson in 1903.

By 1960 the peregrine’s North American population had crashed, mostly as a result of the effects of pesticides introduced after World War II, especially DDT. DDT enters the falcon’s system through its consumption of poisoned prey, especially insect-eating birds, and interferes with the hormones regulating a female peregrine’s reproductive system. As a result, she lays soft-shelled eggs that might be crushed by the incubating bird or that otherwise fail to hatch. The peregrine falcon population had reached critically low numbers in North America by 1970, when it was listed as nationally endangered. It was among the species to be added to the initial list of nationally endangered species when the Endangered Species Act was enacted in 1973, thus becoming eligible for federal research and population recovery efforts.

It was not uncommon during the late 1960s to walk across the University of Nebraska’s Lincoln campus and see dead and dying songbirds after DDT had been sprayed to try to control summer mosquito populations. The publication of Rachel Carson’s book Silent Spring in 1962 had alerted the country to the dangers of using such pesticides, but it took another decade of political and legal fighting before the sale and use of DDT in the United States was finally prohibited. In the late 1960s I published a community columnist piece in the Lincoln Journal, pointing out the health perils to both humans and wildlife of using DDT. I very soon received an irate letter from one of the vice presidents of Vesicol, the largest American producer of DDT and other agricultural chemicals, telling me that the substance was completely harmless, and that to prove it he sprinkled a teaspoonful of DDT on his breakfast cereal every morning! I didn’t reply but have often wondered how much longer he survived.

The increasing construction of high-rise buildings in many U.S. cities has had an unexpected benefit for peregrines. Evidently accepting the idea that skyscrapers are nothing but artificial cliffs, peregrines began nesting on their highest ledges as their numbers slowly began to increase in the late 1970s. Cities not only provide such potential nest sites but also an abundant supply of prey in the form of urban birds, such as rock pigeons and starlings, and freedom from predators of newly fledged birds, such as great horned owls and golden eagles. Buildings that are at least ten stories high are selected; such heights are apparently the lowest that the birds will accept.

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