JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 150.135.239.97 on Mon, Abstract: We studied survival of radiocollared elk (Cervus elaphus) calves in Yellowstone National Park from 1987 to 1990, and survival of calves computed from population estimates from 1968 to 1992. We hypothesized that summer and winter survival of elk calves and mass of neonates were inversely related to population size, measures of environmental severity, and timing of births. Herd-wide survival estimates based on winter counts, reported harvests, and herd classifications, suggested that winter survival of elk calves was related inversely to estimated size of the elk population during winter (P = 0.0002), but we found no correlation with an index of winter severity (P = 0.51). Summer survival of elk calves also was correlated inversely with the estimated size of the elk population the previous winter (P = 0.03). Summer survival of radiocollared calves averaged 0.65 (n = 127 marked calves) from 1987 to 1990, the losses mostly due to predation (22%). Winter survival of calves averaged 0.72 (n = 88 marked calves entered the winter period), with losses due mostly to malnutrition (58%). Summer survival of radiocollared calves was positively correlated with estimated birth weight (P = 0.001). Survival of radiocollared calves during winters 1987-90 was correlated positively with early calving and mildness of the winter (in contrast to herd-wide survival estimates), and was inversely correlated with estimated elk population size that winter (P = 0.006). Winter survival of radiocollared calves was lower during 1988-89 following the drought and large fires than the other 3 winters (P < 0.001). Predation on elk calves during summer doubled after the drought and fires of 1988 (13% calf losses to predation before the fires vs. 29% after the fires). Potential compensation existed between components of calf mortality: predators killed more light (P = 0.041) and more late born calves (P = 0.146); calves were born later and lighter (P = 0.048) following severe weather conditions; and heavier born calves survived at a higher rate (P = 0.006). Our results are consistent with the hypothesis that density-dependent mortality of calves during winter due to malnutrition, and summer mortality of calves due to predation were partially compensatory but severe environmental conditions produced largely additive components to both summer (increased predation) and winter (increased malnutrition) mortality. J. WILDL. MANAGE. 61(1):12-25

We analyzed factors that contributed to the success of 100 translocations of bighorn sheep within six western states between 1923 and 1997. We categorized the populations as unsuccessful (i.e., extirpated or remnant, <29 animals), moderately successful (30–99 animals), and successful (100–350 animals) by the end of the study period in 1997. Thirty of the translocated populations were unsuccessful (n = 13 were extirpated and n = 17 were remnant), 29 were moderately successful, and 41 were successful (21 ± 1.3 [SE] years of information per translocation). Translocations were less successful when domestic sheep were located within 6 km of the known bighorn sheep use areas (logistic regression, p = 0.052). Grazing of cattle on the same range also negatively influenced success (p = 0.004). Use of indigenous versus previously translocated source stocks increased success (p = 0.084). The translocation was twice as likely to be successful when indigenous herds were used as sources (p = 0.043), but mixing genetic stocks (p = 0.381) or later additional augmentations did not influence success (p = 0.095). Annual migrations by newly established translocated populations increased success (p = 0.014). We recommend translocations of founder groups of bighorn sheep from indigenous sources into large patches of habitat that promote movements and migrations, and with no domestic sheep present in the area.