Captive Breeding and Reintroduction Evaluation Criteria: a Case Study of Peninsular Bighorn Sheep

Captive breeding and reintroduction programs are rarely evaluated, and assessment criteria vary widely. We used the following criteria to evaluate a bighorn sheep (Ovis canadensis) augmentation program: (1) survival and recruitment rates in the captive population, (2) survival of released animals, (3) recruit- ment of released animals, (4) growth rate of the reintroduced or augmented population, and (5) establish- ment of a viable wild population. Captive bighorn survival and recruitment was high, averaging 0.98 (SD = 0.05) and 71.0% (SD = 19.4), respectively. Annual survival offree-ranging captive-reared bighorn (n = 73, x = 0.80, SD = 0.11) did not differ (Z = -0.85, p = 0.40; n = 14) from survival of wild-reared bighorn (n = 43, x = 0.81, SD = 0.12). Recruitment was unusually low for both captive-reared (x = 13.7%, SD = 0.24) and wild-reared ewes (x = 13. 7%, SD = 0.20). Although reintroduction did not result in population growth or es- tablishment of a viable population, it helped prevent extirpation of the reinforced deme, preserved metapopu- lation linkage, and aided habitat preservation. Chronic low recruitment and low adult survivorship pre- cluded achievement of criteria 3-5. Environmental conditions in the release area also appeared to hinder program success. Standard evaluation criteria for ongoing reintroductions allow for informative assessments andfacilitate comparisons needed to refine reintroduction science as a recovery toolfor threatened or endan- gered populations.