In 1979, only one Peregrine Falcon pair (they fledged two young) and a single adult male were located. A population decline east of the Cascades began in rhe 1930's, probably resulting from a climatic change (drought); however, a statewide decline began in the late 1940's, accelerated in the 1950's, and by the 1960's few pairs remained. The statewide decline closely paralleled the pattern of DDT use. Furthermore, DDE was found in membranes of peregrine eggs from nearby California as early as 1948. Moreover, an unhatched Peregrine Falcon egg found at the Oregon eyrie in 1979 contained 19 ppm DDE and lesser amounts of other contaminants. The eggshell was 19% thinner than normaL The future of the nearly extirpated Peregrine Falcon in Oregon remains uncertain in spite of improved water and habitat conditions in eastern Oregon. Reintroduction of captive-bred birds seems to be the last hope.
Additional publication details
Decline and present status of breeding peregrine falcons in Oregon