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Wednesday, 09 August 2006 00:00

Peregrine falcons make a tenuous comeback

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Peregrine falcons, a recovering endangered species, once again nested successfully this spring on Whiteside Mountain in Highlands.

Volunteers from the Highlands Plateau Audubon Society chapter aided the N.C. Wildlife Resources Commission in monitoring the nesting area. Two young falcons were born and began flying in late May.

Peregrines are fast flyers and may reach speeds greater than 200 miles per hour in a dive. They prey on birds that range in size from songbirds to waterfowl, which they capture in mid-flight. In Western North Carolina, small to medium sized, slow-moving birds such as blue jays and grackles comprise the bulk of the falcons’ diet.

Peregrines require large territories. They nest on sheltered ledges on steep cliffs to keep away predators and provide protection from the elements.

Peregrine falcons roam a large territory to catch the prey they need. As a result, pairs will not nest near each other. In Western North Carolina, the two closest nest sites are more than five miles apart.

Peregrines nested regularly in North Carolina until the 1950’s when they disappeared from the entire eastern United States. Their disappearance from the eastern U.S., as well as their decline in large areas of the western U.S. and Europe were caused by environmental contaminants, including the pesticides DDT and dieldrin.

The pesticides got into the water and were absorbed by insects. Small birds ate contaminated insects, and became contaminated themselves. Peregrines ate the contmainted small birds, and by now the multiplier effect of the pesticides in the food chain caused concentrations high enough to kill many birds directly. In addition, the pesticides interfered with calcification of eggshells, resulting in thin eggshells that were crushed as the parents sat on them during incubation.

In 1970, the U.S. Fish and Wildlife Service listed the Peregrine falcon as an endangered species. Recognizing the effect of DDT, the Environmental Protection Agency banned the pesticide from use in the U.S. in 1972.

Attempts at restoring the peregrine falcon began in 1974 with the first release of captive bred falcons. The N. C. Wildlife Resources Commission began releases in 1984. Eighty juvenile peregrines had been released in the state by 1991. An additional 12 birds were released in 1996 and 1997 to increase the population in the Southern Appalachian Mountains. Falcon watchers first observed the species nesting on Whiteside Mountain in 1988 and the birds have continued to nest there each year. Approximately 11 nesting pairs of peregrines live in North Carolina. Whiteside has been the most successful nesting site in the state with 39 chicks fledged from the site in the last 18 years. Although the U.S. Fish and Wildlife Service removed the peregrine from the Federal Endangered Species list in 1999, it remains protected under the N.C. Endangered Species law and at the federal level by the Migratory Bird Treaty Act.

Survival of peregrines in N.C. remains tenuous. There are relatively few nesting pairs, and the mortality rate for young birds is high. Here’s how you can help:

• Donate to the N.C. Nongame and Endangered Wildlife Fund (1722 Mail Service Center, Raleigh, N.C. 27699 – www.ncwildlife.org)

• Limit use of pesticides and herbicides whenever possible to prevent risk of environmental pollution.

• Avoid rock climbing in areas where peregrines nest during their breeding season, February through June. The area on Whiteside where peregrines nest is closed for rock climbing during this period.

• Join Highlands Plateau Audubon, www.main.nc.us/nas-hpc, or other conservation organizations to learn more about peregrines and related conservation issues.

— Becky Johnson

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