Morbidity, survival and productivity of rehabilitated Peregrine Falcons in the upper midwestern U.S.

We examined morbidity, survival and breeding success of 168 free-ranging, midwestern Peregrine Falcons (Falco peregrinus) submitted to The Raptor Center, University of Minnesota, for veterinary care during 1986-94. Field data and returns of banded birds were used to compare postrelease survival and productivity of rehabilitated Peregrine Falcons to survival and productivity of nonrehabilitated wild peregrines. Falcon morbidity and treatment outcomes were analyzed from medical records. Approximately 81% (N=137) of Peregrine Falcons suffered traumatic injuries consisting of fractures, dislocations and soft tissue trauma. Most injuries were caused by collisions with buildings, motor vehicles and utility lines. Forty-one percent (N=66) of 161 Peregrine Falcons were successfully treated, rehabilitated and released into the upper Midwest. Minimum estimated survival rates of rehabilitated peregrines were approximately 20% for ≥3 mo and nearly 14% (N = 9) for ≥1 yr. The 1-yr estimated minimum survival rate was similar to that of banded, nonrehabilitated peregrines from the same population. Over 10% (N=7) of rehabilitated Peregrine Falcons formed territorial pairs, and 6% (N= 4) nested, producing 24 fledglings over 1-5 yr. Mean brood size at fledging was 3.0 young, similar to the average brood size of successful peregrine pairs throughout the Midwest. This study demonstrates that, with proper veterinary care and physical conditioning, some injured Peregrine Falcons can be restored to good health and compete successfully in the wild. Rehabilitation of endangered raptors may enhance population growth during early stages of species recovery.