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Captive Breeding Program

Newly Hatched Peregrine Falcon (Photo: Antonia Varleye)For many years, our main purpose was captive propagation and release of endangered birds of prey; including peregrine, aplomado, and bat falcons; Harris's hawks, and elf owls. Many of the peregrine young hatched at our facility were from wild-laid peregrine eggs thinned by DDE. In removing them from wild nests for incubation in captivity, our aim was to prevent them from breaking or becoming desiccated in the nest due to excessive evaporation through the thinned shell. Other young were produced by our captive pairs of adult anatum peregrines, which bred naturally in large, open air aviaries.

Falcon Eggs in an IncubatorEach egg was measured, and a calculation run to determine the ideal amount of weight (moisture) it should lose daily to achieve the approximately total 15% weight loss expected by hatching time. This was controlled by the use of incubators of varying humidity. Each egg was weighed nightly and moved to the appropriate humidity as needed.

We have released over 1000 young peregrine falcons in California, Oregon, Washington, and Nevada combined over the years, with the goal of augmenting the recovery of peregrines in these states. Three release techniques were used; direct-fostering, cross-fostering, and hacking. Most of these birds are gone now, but their wild progeny of several generations continue to reproduce and expand in number.