Peregrine Falcon Decline

The catastrophic decline of the American Peregrine Falcon (Falco peregrinus anatum) began with the introduction of DDT and other chlorinated hydrocarbons in the 1940’s. The contaminants affected calcium metabolism, causing egg shell thinning and peregrines were unable to produce young. Peregrine falcon populations crashed over most of their known range. By the early 1980’s, we could not locate a single nesting peregrine in the state of Montana.

The Peregrine Fund, with cooperation from many agencies and individuals, first responded to the catastrophic decline in American Peregrine Falcon populations in Montana with a reintroduction program begun at the Red Rocks National Wildlife Refuge in 1981. By 1998, the Peregrine Fund had released a total of 555 young birds at 26 different hack sites in Montana. Ralph Rogers released an additional 62 Peregrine Falcons at two hack sites near the eastern Missouri River. Wild populations produced 120 young during the 1994-98 period. These introductions and the increase in both number and productivity of wild eyries have helped reestablish a viable Peregrine Falcon population in Montana. By 1994, a mix of state, federal, and private biologists (Montana Peregrine Falcon Working Group) documented 13 known active Peregrine Falcon eyries. The number of known eyries remained stable at about 17 until the beginning of more intensive survey efforts in 1999 when 27 eyries were found.
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