Survival of rehabilitated and released red-tailed hawks (Buteo jamaicensis)

Abstract

Wildlife rehabilitation provides responsible care for sick, injured or orphaned wild animals with the goal of releasing fully recovered individuals back into the environment. Post-release survival data for these animals remain sparse but necessary to measure and assess the impact of wildlife rehabilitation as a conservation strategy. This study used national banding data to quantitatively compare annual survival of wild-caught (non-rehabilitated) and rehabilitated red-tailed hawks (Buteo jamaicensis). In addition, 13 rehabilitated and released red-tailed hawks from Dane County Humane Society’s Wildlife Center (DCHS, Madison, WI) were monitored using radio telemetry. Annual survival of rehabilitated and radio-tagged red-tailed hawks from DCHS was 36% over 85 weeks of monitoring. Nationally, wild red-tailed hawk annual survival (0.777; 95% CI [0.768, 0.777]) was largely equivalent to estimates reported in other published studies. These estimates reflect average survival over 40 years in a fully time-dependent model (variance component estimated using the Delta Method; Powell 2007). Rehabilitated red-tailed hawks had an annual survival of 0.549 (95% CI: 0.523, 0.575]) over 43 years. These values reflect model-averaged estimates from time-independent survival models (recovery was time dependent) that were equivalent in terms of likelihood (Brownie = Seber = wi = 0.50). Consequently, survival of rehabilitated red-tailed hawks was approximately 22% lower than wild-caught individuals. Furthermore, young (hatch-year) red-tailed hawks experienced increased mortality (34%) relative to those rehabilitated as adults (0.255; 95% CI [0.199, 0.321] versus 0.598; 95% CI [0.571, 0.624], respectfully). The results of this study demonstrate the need for additional post-release monitoring and may guide future management decisions regarding wildlife rehabilitative criteria, practice and viability.