When Is A Peregrine Like A Phoenix?
When It Comes Back from Near-Extinction
Imagine a world without insects and without birds. Instead of waking up to their
buzzing, chirping and songs, there would be only silence. Like a series of dominoes, the
effects would widen. Scores of plant species would be dying out, because the bees and
other pollinators were gone. The animals that depended on those plants would die out next.
Eventually, humankinds existence would be threatened.
Rachel Carson imagined such a world in her ground-breaking book "Silent
Spring," published in 1962. She rocked the world. Millions were stunned to discover
the deadly consequences of our increasing dependence on potent pesticides. Poisons like
DDT (dichlorodiphenyltrichloroethane) slowly accumulated in each stage of the food chain
almost destroying some birds of prey like peregrine falcons and even our national symbol,
the bald eagle.
People were not immune. Testing indicated high levels of the powerful chemical in
people, too. Now, DDT, once touted as perfectly safe for people, is listed as a carcinogen
(cancer-causing agent) and has been linked to breast cancer.
DDT and related chemicals known as organochlorines first came into widespread use after
World War II. DDT, for example, was heavily used in the United States because it was long
lasting and highly effective at killing insects that decimated crops. Even today, some
countries use it to kill mosquitoes in an attempt to reduce malaria and many
less-developed nations still use these poisons in agriculture. But it soon became apparent
that harmful insects werent the only victims. Beneficial insects were affected, too.
Birds and other insect-eating creatures were being slowly poisoned. The effect was most
visible in the birds of prey especially peregrine falcons.
Before World War II there were thousands of nesting pairs of peregrines in the lower 48
states. By about 1964-65, the peregrine was extinct east of the Mississippi and there were
only 39 known pairs west of the Mississippi. In the northern Great Plains South
Dakota, North Dakota, Montana the birds were completely wiped out.
Chemicals like DDT interfered with the reproductive cycle of raptors. The poison built
up in the falcons bodies as they ate birds that, in turn, had eaten insects and
plants contaminated with the chemicals. The result was diminished fertility, plus eggs
with shells so thin, they broke under the parents weight.
The growing awareness of the widespread toxic effects of DDT and similar chemicals
finally led to action. In the late 1960s and early 1970s, scientists and environmentalists
began organizing to find ways to counteract the damage. In 1970, DDT was banned in Canada.
It was banned in the United States in 1972. But it was almost too late.
Falconers played a big part in saving the peregrine. Dr. Tom Cade, then a professor at
Cornell University, established The Peregrine Fund in 1970, and gathered peregrines to
begin a captive breeding project. Some were from wild stock, but many came from falconers
from throughout the United States and Canada. Today, The Peregrine Fund estimates it has
released some 4,000 birds.
One possible side effect of captive breeding programs has been the appearance of
peregrines in more heavily populated areas, where they have been nesting in tall
buildings, church towers and power plant smokestacks.
Their incursions into the human sphere have made them very popular. Bird watchers line
up in metropolitan areas like Toronto and New York City to view peregrines that are
nesting in skyscrapers. In the Midwest, power plants have been popular nesting sites for
the raptors (see http://www.nspco.com/nspbird99.htm
for a Webcam look at Mae, a peregrine who returns yearly to a Northern States Power
smokestack in Minnesota).
Peregrines are one of the success stories of the environmental movement. The birds,
once near extinction, were removed from the Endangered Species List on Aug. 25, 1999.
Scientists like Cade, however, warn that the birds will have to be carefully monitored.
They winter in South America, where DDT is still in use. Peregrines still have DDT in
their systems and eggshells are still thinner than they should be.
In addition, the birds are still scarce in some traditional nesting areas, including
the Northeastern U.S. and the northern Great Plains. Falconer Dan OBrien, author and
subject of the PBS and South Dakota Public TV program A FALCONERS MEMOIR, is working
to reintroduce the species in his area, just North of the Black Hills of South Dakota.