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) recruitment of released animals, (4) growth rate of the reintroduced or augmented population, and (5) establishment 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 of free‐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 establishment of a viable population, it helped prevent extirpation of the reinforced deme, preserved metapopulation linkage, and aided habitat preservation. Chronic low recruitment and low adult survivorship precluded 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 and facilitate comparisons needed to refine reintroduction science as a recovery tool for threatened or endangered populations.

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Q fever is a rare illness in the Southern California desert. During the past 34 years only 6 patients have been diagnosed with the disease at the Eisenhower Medical Center, a referral center for much of the desert and surrounding mountains. In all but 2 instances, Q fever was identified in patients who have been in contact with imported domestic sheep who are brought to the desert to graze and lamb in the fall and winter. The sheep are sent back to Idaho, Wyoming, and Montana in the spring. With frequent infection by Coxiella burnetii established in domestic sheep, we elected to study the prevalence of complement fixing antibodies to Coxiella burnetii in native bighorn sheep who reside in the lower levels of the mountains surrounding the desert. From 1992 to 1999, of 268 serum samples drawn from male and female lambs and adult sheep, 27 tested positive (10%), which is strikingly low when compared with Dall sheep in Alaska (12 of 15), kangaroos, wild rabbits, and brown rats. Because changes have been made in Peninsular bighorn sheep habitat since the animals were listed as endangered in 1998, further follow-up in Q fever serology testing will be of interest.

Peninsular bighorn sheep (Ovis canadensis nelsoni) are found exclusively in Southern California and Baja Mexico. They are federally endangered due to multiple threats, including introduced infectious disease. From 1981 to 2017, we conducted surveillance for 16 pathogens and estimated population sizes, adult survival, and lamb survival. We used mixed effects regression models to assess disease patterns at the individual and population levels. Pathogen infection/exposure prevalence varied both spatially and temporally. Our findings indicate that the primary predictor of individual pathogen infection/exposure was the region in which an animal was captured, implying that transmission is driven by local ecological or behavioral factors. Higher Mycoplasma ovipneumoniae seropositivity was associated with lower lamb survival, consistent with lambs having high rates of pneumonia‐associated mortality, which may be slowing population recovery. There was no association between M. ovipneumoniae and adult survival. Adult survival was positively associated with population size and parainfluenza‐3 virus seroprevalence in the same year, and orf virus seroprevalence in the previous year. Peninsular bighorn sheep are recovering from small population sizes in a habitat of environmental extremes, compounded by infectious disease. Our research can help inform future pathogen surveillance and population monitoring for the long‐term conservation of this population.