Because of the poor colonizing ability of bighorn sheep, previous transplant programs have attempted to reestablish populations in localized areas where they have been extirpated or to expand populations where they have been reduced. The overall objective of this study was to evaluate the success of the augmentation by examining (1) survivorship, (2) lamb production, (3) dispersal, (4) 95% and 50% adaptive kernel, fixed kernel, and minimum convex polygon home-range size, (5) 95% and 50% adaptive kernel planimetric and surface area estimates, (6) interannual variation in home-range size, (7) habitat use, (8) escape terrain and buffer terrain,(9) an animal location based model (ALBM), (10) an escape terrain and buffer model (ETBM), (11) the habitat evaluation procedure (HEP) of Sweanor et al. (1995) and Zimmerman et al. (2006), (12) degree of population subdivision (Fst) between the North and South Units in BNP, 13) observed heterozygosity (Ho), expected heterozygosity (He), number of alleles per locus, average number of alleles per locus (Ne), and the number of effective alleles (Nea) of bighorn sheep at BNP pre- and post-augmentation.
Eighteen of 23 translocated bighorn sheep survived and remained with the sub-population. In 2005, 10 lambs were born and 9 (5 females, 4 males) survived to 1 year of age. In 2006, 9 lambs were born and 8 (4 females, 4 males) survived to 1 year of age. In 2007, 8 lambs were born and 7 (5 females, 2 males) survived to 1 year of age.
The 95% adaptive and fixed kernel home-range estimates did not differ (P = 0.096) and the 95% adaptive kernel home-range estimate and the minimum convex polygon estimate did not differ (P = 0.211). The 50% fixed kernel home-range estimate was greater (P = 0.001) than the 50% adaptive kernel home-range estimate. The 95% home-range size increased (P = 0.007) between year 1 of the study and year 2 of the study, but the core estimates did not differ ( P = 0.450) between years.
Translocated and resident bighorn sheep were located on more vertical slopes (P < 0.001), closer to wet areas (P < 0.001), closer to roads (P < 0.001), and closer to escape terrain (P < 0.001) compared with respective random locations. Translocated bighorn sheep were located on more (P < 0.001) horizontal slopes, closer to wet areas (P < 0.001), and closer to roads (P < 0.001) compared with resident bighorn sheep. Translocated and resident bighorn sheep locations did not differ (P = 0.800) in their proximity to escape terrain.
Within the 981 km2 study area evaluated in BNP, approximately 464 km2 and 367 km2 of suitable bighorn sheep habitat was identified by the ALBM and ETBM, respectively. The Sweanor et al. (1995) and Zimmerman et al. (2006) models identified approximately 377 km2 and 599 km2, respectively, of suitable bighorn sheep habitat in BNP. Based on the ETBM, 4,007.2 km2 of 108,362 km2 of potential bighorn sheep habitat was identified as suitable for bighorn sheep in western South Dakota.
DNA was extracted and successfully genotyped from 95 individuals from 7 time periods (e.g., bighorn sheep that occurred prior to 1925 [Historic], 1992, 1996, 1998, adult males captured prior to the augmentation [Adult04], augmented bighorn sheep [NMIntro], offspring of the augmentation [Off0506]). Based on all loci of resident bighorn sheep, rate of expected heterozygosity loss was 9.8% in 1992–1998 and 5.05% in 1998–2004, with a total decrease of 1.1% per year in 1992–2004. (Abstract shortened by UMI.)