On 20 August, the peregrine
falcon was officially removed from the Federal
List of Endangered Species, The
Peregrine Fund and The Raptor Center
were happy to announce the delisting showing how much of a recovery the
Peregrine Falcon has truly made from the near devastation and extinction from
organochlorides and habitat destruction. Today
in nearly every major city, there is an established population among the high
rises and busy city streets. This
versatile bird has come to challenge everything we had to protect it, and move
beyond our expectations but the fight is not over.
There are still high risks for the once endangered birds and the price of
reintroduction has been high, falconers from around the world were sought out
for their licensed birds and breeding populations to release the precious falcon
again into the wild. With the help
of restorative efforts from the 1970’s on were able to correct a mistake that
has been long in the running but we must continue the process of education and
vigilance for future generations.
The birds have been used world wide for falconry, but in the mid 1960’s a drastic decline in populations amassed. In August 1965, a group of falcon experts met at the University of Wisconsin in Madison the mark the unprecedented population crashes of Peregrine Falcons in North America and Europe. It helped secure restrictions on the use of DDT and dieldrin in several western industrialized countries in the 1970’s. Even after 10-15 years of the virtual absence of DDT application in North America, there continue to be puzzling, high levels of DDE residues and eggshell thinning in some nesting Peregrines in the western US and in some prey species. The sources of this contamination, long suspected to be from Latin America, were then discussed at the Sacramento Conference. Meanwhile, restoration efforts of the Peregrine populations by captive propagation and the release of captive progeny into the vacant range have become major undertakings in Canada, US, West Germany, and Sweden. As a result of these “recovery programs” Peregrines are nesting in locales where they have been absent for 20-30 years as well as new sites like skyscrapers, bridges, lighthouses, and nesting towers in coastal salt marshes.
Nov. 1985, more raptor biologist and Peregrine specialists met together in Sacramento California, for a three-day international conference to discuss Peregrine biology and conservation.
Numbers of the North American Peregrines rarely exceeded the high densities found in some other parts of the world, especially the British Isles in the past before the devastatingly declines. Estimates of the number of known Peregrine-nesting territories in various North American regions are difficult to observe. Many of the “historical” sites have come to light only in recent years, as researchers try to reconstruct the former region-by-region status of the species. They have scoured literature, field notes of long-dead collectors, and specimen records for this research.
In the 1940’s there was nothing to suggest that the Peregrine was in decline in North America. Although about 10-18% of the historical eyries had fallen into disuse for a variety of reasons.
By 1962 it was rumored that Peregrine productivity was near zero in the northeastern states. Not one occupied cliff was reported among 109 historical eyries to have a peregrine nesting. In the more remote Peregrine populations of Alaska and artic Canada, a decline apparently occurred later, suggesting a gradual decline may have already been under way as early as the 1950’s. At the time of the Madison conference, only 33% of all known eyries in the Rocky Mountains were still occupied. The Peregrine was also gone as a breeding species form the southern part of California and the northern half of Baja California, and major declines had also occurred in other parts of the western US and in much of southern Canada and even the Northwest Territories.
Causes of the decline:
Reproductive Failure
Eggshell Thinning
Singling Out DDE and DDT
Climatic change
Conference summary for Peregrine decline
1) “overkill” – direct exploitation or persecution by humans, including shooting, poaching of adults, young and eggs, and poisoning
2) Destruction or degradation of natural habitats
3) Chemical pollution. Direct killings or molestation by mass as the least import threat to birds of prey, particularly the Peregrine.
The loss of habitat was defined as ultimately the most important factor controlling populations, but chemical pollution as the most immediately important.
Other pollutants that cause eggshell thinning – DDE, PCB, dieldrin, heptachlor expoxide, and mercury
Peregrines have suffered diverse forms of human-induced mortality from time immemorial, and the number and variety of threats to the Peregrine have increased in our highly technological society. The bans on the use of DDT in a number of countries have unquestionably allowed the recovery of many Peregrine populations. Taken together, these bans represent the single most important conservation measure that could be taken to save the Peregrine and many other bird species. And today we can see those results with the delisting of the Peregrine Falcon off the Endangered Species List.
Resources:
Emma Ford, Falconry – Art and Practice, Wellington House 1992
1988 The Peregrine Fund. Inc. Boise, Idaho
Edited by Tom Cade, James Enderson, Carl Thelander, and Clayton M. White
Hawks In Flight, Pete Dunne, David Sibley, and Clay Sutton
Sheryl De Vore, Northern Flights - Tracking the Birds and Birders of Michigan's Upper Peninsula, Mountain Press Publishing Comany 1999.
