Translocations as a tool for restoring populations of bighorn sheep

We analyzed factors that contributed to the success of 100 translocations o f bighorn sheep within six western states between 1923 and 1997. We categor ized the populations as unsuccessful (i.e., extirpated or remnant, <29 anim als), moderately successful (30-99 animals), and successful (100-350 animal s) by the end of the study period in 1997. Thirty of the translocated popul ations were unsuccessful (n = 13 were extirpated and n = 17 were remnant), 29 were moderately successful, and 41 were successful (21 +/- 1.3 [SE] year s of information per translocation). Translocations were less successful wh en domestic sheep were located within 6 km of the known bighorn sheep use a reas (logistic regression, p = 0.052). Grazing of cattle on the same range also negatively influenced success (p = 0.004). Use of indigenous versus pr eviously translocated source stocks increased success (p = 0.084). The tran slocation was twice as likely to be successful when indigenous herds were u sed as sources (p = 0.043), but mixing genetic stocks (p = 0.381) or later additional augmentations did not influence success (p = 0.095). Annual migr ations by newly established translocated populations increased success (p = 0.014). We recommend translocations of founder groups of bighorn sheep fro m indigenous sources into large patches of habitat that promote movements a nd migrations, and with no domestic sheep present in the area.