Custer State Park Research Articles

Occurrence of North American Porcupine (Erethizon dorsatum) in the Black Hills, South Dakota

During the twentieth century, the North American porcupine (Erethizon dorsatum) was common in the Black Hills of western South Dakota and northeastern Wyoming. However, the low number of recent observations in the region has led to concern that porcupine populations have declined. We conducted systematic surveys to assess porcupine occurrence at two hundred and sixty-three 1-ha sites in the Black Hills National Forest, Custer State Park, Jewel Cave National Monument, Mount Rushmore National Memorial, and Wind Cave National Park during 2016–2017. We observed no porcupines or recent feeding sign. We also noted few recent observations in information compiled from online databases and from other natural resource surveys with which we have been involved in the South Dakota Black Hills. Given the apparent abundance of porcupines in this area in the twentieth century, our results suggest that populations have declined dramatically. Predation by mountain lions (Puma concolor), habitat loss, and human-caused mortality are potential contributing factors, but estimating the degree of population declines and assessing hypotheses about the causes are hindered by a lack of long-term data on the region's porcupine populations. Moreover, accounts of the region's mammalian fauna suggest that porcupines were not abundant in the region during the late 1800s but became common in the early twentieth century.

Removal of chronic Mycoplasma ovipneumoniae carrier ewes eliminates pneumonia in a bighorn sheep population.

Chronic pathogen carriage is one mechanism that allows diseases to persist in populations. We hypothesized that persistent or recurrent pneumonia in bighorn sheep (Ovis canadensis) populations may be caused by chronic carriers of Mycoplasma ovipneumoniae (Mo). Our experimental approach allowed us to address a conservation need while investigating the role of chronic carriage in disease persistence.We tested our hypothesis in two bighorn sheep populations in South Dakota, USA. We identified and removed Mo chronic carriers from the Custer State Park (treatment) population. Simultaneously, we identified carriers but did not remove them from the Rapid City population (control). We predicted removal would result in decreased pneumonia, mortality, and Mo prevalence. Both population ranges had similar habitat and predator communities but were sufficiently isolated to preclude intermixing.We classified chronic carriers as adults that consistently tested positive for Mo carriage over a 20‐month sampling period (n = 2 in the treatment population; n = 2 in control population).We failed to detect Mo or pneumonia in the treatment population after chronic carrier removal, while both remained in the control. Mortality hazard for lambs was reduced by 72% in the treatment population relative to the control (CI = 36%, 91%). There was also a 41% reduction in adult mortality hazard attributable to the treatment, although this was not statistically significant (CI = 82% reduction, 34% increase). Synthesis and Applications: These results support the hypothesis that Mo is a primary causative agent of persistent or recurrent respiratory disease in bighorn sheep populations and can be maintained by a few chronic carriers. Our findings provide direction for future research and management actions aimed at controlling pneumonia in wild sheep and may apply to other diseases.

Adult Pronghorn (Antilocapra americana) Survival and Cause-specific Mortality in Custer State Park, S.D

Although understanding natural mortality rates of ungulate populations is essential for effective management, published data on adult survival from unharvested pronghorn (Antilocapra americana) populations in the Northern Great Plains is limited. We estimated seasonal adult survival rates and cause-specific mortality of an unharvested pronghorn population in Custer State Park, S.D. We assessed the relative importance of sex, age, year, and season in explaining pronghorn survival rates using an information-theoretic approach. We captured and radio-collared 26 male and 24 female adult pronghorn from fall 2005 through spring 2008. We observed higher predation rates and lower survival of adult pronghorn in CSP compared to other populations in the region, but similar to the pronghorn population in Yellowstone National Park. We documented 23 deaths (10 females, 13 males) of the 50 radio-collared pronghorn from Nov. 2005–Nov. 2008. Predation by mountain lions (Puma concolor) and coyotes (Canis latrans) accounted for 69.5% of all mortalities. The season model received the greatest support although there also was strong support for the season × sex model. Seasonal survival for males and females was >0.90 for the winter-grouping and breeding seasons but fell to 0.791(95% CI 0.644–0.887) and 0.837 (95% CI 0.706–0.916) for females and males, respectively, during the small group – parturition season. A dense predator population, as well as a higher vulnerability to predation when pronghorn are solitary or in small groups, may explain the lower survival during these time periods. If population estimates fall below management goals, management actions aimed at reducing predator cover may be beneficial to adult pronghorn. Managers of pronghorn populations near forested and rugged areas and that are sympatric with dense predator populations should consider adult survival may be lower than observed in Great Plains populations.

Importance of visibility when evaluating animal response to roads

Roads increase risk to animals via direct and indirect mechanisms yet, both positive and negative effects of animal space use in relation to roads have been reported. These contrasting reports may not actually represent animal ecology, but could be a product of the primary variable used to test the relationship between animals and roads. Animal‐road associations are often evaluated using Euclidean distance. Euclidean, or straight‐line, distance fails to account for the screening effects of vegetation and topography and may document spurious relationships. We evaluated the influence of Euclidean distance, visibility from road and forage quality on summer space use for male elk Cervus elaphus and female elk subherds in Custer State Park, South Dakota, USA. Models that included interactions with visibility from road metrics outperformed models that included only Euclidean distance to road as main effects. Elk response to roads varied by sex and road type, which functioned as an index for vehicle use. Male elk selected habitat away from roads with the greatest vehicle use, an effect that was greater if habitat was visible from those roads. Female elk tended to select habitat with high forage quality in areas visible from roads closed to vehicle use. Interestingly, both male and female elk selected habitat away from roads with secondary vehicle use and near to roads devoid of traffic, regardless of visibility. Our analysis highlights the importance of including both Euclidean distance and visibility from road metrics. Road effects research may be incomplete without consideration of visibility from roads, particularly for large mammals in landscapes with intense road use.

Profit, Preservation, and Shifting Definitions of Bison in America

In the first decades of the twentieth century, populations of North American bison increased following the creation of several government herds while economic demand for bison decreased. Early preservationists believed that the animals would never return to a position of economic value, and those few individuals attempting to profit from the species found limited markets for their product. The experience of Custer State Park in South Dakota blurs the distinctions between profit and preservation as the managers of that herd attempted to generate revenue from their bison, first through live sales and later by slaughtering some animals for meat. Limited demand for buffalo meat as an exotic addition to Christmas dinners continued, but by the 1930s mainstream economic demand for bison all but disappeared. Faced with growing buffalo populations, federal government officials created tribal herds on the Crow and Pine Ridge reservations. The entry of the United States into World War II resulted in a domestic rationing of meat that led to the expansion of operations at Custer State Park and the elimination of the Pine Ridge tribal herd. The story of bison's recovery in the first half of the twentieth century shows that environmental factors and economic considerations of animal preservation are far from antagonistic; they are inseparable.

RELATIONSHIPS AMONG FECAL LUNGWORM LOADS, FECAL GLUCOCORTICOID METABOLITES, AND LAMB RECRUITMENT IN FREE-RANGING ROCKY MOUNTAIN BIGHORN SHEEP

Most wild Rocky Mountain big-horn sheep (Ovis canadensis canadensis) in northern latitudes are infected with lungworms. Indirect effects of lungworms on bighorn sheep are unknown, but high pulmonary burdens might increase stress (i.e., elevated glucocorticoid levels), and chronic stress could in turn decrease fitness. We hypothesized that high lungworm burdens in Rocky Mountain bighorn ewes increase stress, thereby increasing lamb mortality. To test our hypothesis, one subherd of bighorn sheep in Custer State Park, South Dakota was provided a free-choice loose mineral mix containing the anthelmintic fenbendazole every six weeks from March 1999 to August 2000 to eliminate lungworms; another subherd served as the control. Daily, individually marked ewes were located telemetrically from the ground and uniquely marked animals were observed until they defecated. After the herd moved from the area, fecal samples were collected and stored at -23 C. A consistent number of samples per season per herd (x-=16.56+/-3.99 samples) were collected. Fecal larval lungworm levels (LPG) in the treatment subherd were lower than levels in the control subherd; however, there was no difference in fecal glucocorticoid metabolite (FGM) levels between the two subherds. Fecal glucocorticoid metabolite levels varied by season in both subherds, with levels in winter lower than during the other three seasons. Lamb:ewe ratios were not different between the control and treatment subherds at the end of summer 1999. In contrast, the treatment group had a lower lamb:ewe ratio at the end of summer 2000 despite having lower LPG. However, this result was attributed to lower ewe production, not lower lamb survival. The LPG levels were not correlated with FGM concentrations; instead, FGM levels might reflect normal seasonal patterns. Other factors, including contagious ecthyma, were more important for determining lamb mortality than LPG and FGM levels during our study. We suggest further experimental work over a longer duration to address these relationships.

Cervid forage utilization in noncommercially thinned ponderosa pine forests

To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked plants and percent-plants-grazed were used to evaluate forage utilization. Standing biomass of graminoids, shrubs, and forbs increased (P < 0.05) from unthinned to moderately and heavily thinned stands. Utilization of graminoids and shrubs averaged less than 1% when measured as percent-weight-removed and percent-plants-grazed and did not differ (P > 0.05) across treatments. Forb use averaged less than 5% within sampling periods when measured as percent-weight-removed and percent-of-plants grazed and did not differ among treatments. Results of pellet group surveys indicated that cervids were primarily using meadow habitats. When averaged over the 2 years, forbs were the major forage class in deer diets, whereas graminoids were the major forage class in diets of elk.

Herd organization of cow elk in Custer State Park, South Dakota

Abstract Understanding herd organization is important when considering management alternatives designed to benefit or manipulate elk (Cervus elaphus) populations. We studied the seasonal and annual herd organization of cow elk in Custer State Park, South Dakota from 1993–1997 by examining seasonal subherd range size, spatial arrangement, overlap, and site fidelity. Based on social interaction analyses, we combined locations of radiocol-lared cow elk to delineate subherds. We computed 95% kernel home ranges with least-squares cross validation for each subherd by season and year. Subherd overlap and fidelity by season and year were computed using the Volume of Intersection Index (VI) statistic. We identified 5 relatively discrete, resident cow–calf subherds. We observed little overlap in utilization distributions of adjacent subherds. The mean VI score across all subherds and time points (n=140) was 0.06 (SE=0.009), indicating an average 6% overlap in subherd area utilization. Subherd overlap between pairs ...

Cervid forage utilization in noncommercially thinned ponderosa pine forests

To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked plants and percent-plants-grazed were used to evaluate forage utilization. Standing biomass of graminoids, shrubs, and forbs increased (P 0.05) from unthinned to moderately and heavily thinned stands. Utilization of graminoids and shrubs averaged less than 1% when measured as percent-weight-removed and percent-plants-grazed and did not differ (P 0.05) across treatments. Forb use averaged less than 5% within sampling periods when measured as percent-weight-removed and percent-of-plants grazed and did not differ among treatments. Results of pellet group surveys indicated that cervids were primarily using meadow habitats. When averaged over the 2 years, forbs were the major forage class in deer diets, whereas graminoids were the major forage class in diets of elk.

Cervid forage utilization in noncommercially thinned ponderosa pine forests

Abstract To evaluate effects of noncommercial thinning, utilization of forages consumed by elk (Cervus elaphus L.), mule deer (Odocoileus hemionus Raf.), and white-tailed deer (Odocoileus virginianus Raf.) was measured in ponderosa pine (Pinus ponderosa P. & C. Lawson) stands in Custer State Park, S. D. Treatments consisted of unthinned (control; 22 to 32 m2/ha basal area), moderately thinned (12 to 22 m2/ha basal area), and heavily thinned (3 to 13 m2/ha basal area) stands of ponderosa pine. During June, July, and August, 1991 and 1992, about 7,000 individual plants were marked along permanent transects and percent-weight-removed by grazing was ocularly estimated. Sample plots were established along transects and plants within plots were clipped to estimate standing biomass. Pellet groups were counted throughout the study area to determine summer habitat use of elk and deer. Diet composition was evaluated using microhistological analysis of fecal samples. Average percent-weight-removed from all marked pl...

Microsatellite variation in the reintroduced Pennsylvania elk herd

Relocation programs have restored elk (Cervus elaphus) to portions of its vast historical range. We examine the consequences of these relocation programs by assessing variation at 10 microsatellite loci in three elk herds, a source herd (Yellowstone National Park), a large herd reintroduced from Yellowstone (Custer State Park) and a bottlenecked herd reintroduced from both Yellowstone and Custer (the Pennsylvania herd). Observed single locus heterozygosities ranged from 0.000 to 0.739. Multi-locus heterozygosities ranged from 0.222 to 0.589. Although significant differences were detected among all three herds, the Yellowstone National Park and Custer State Park herds possessed similar levels of variation and heterozygosity, and the genetic distance between these two herds was small. The Pennsylvania herd, on the other hand, experienced a 61.5% decrease in heterozygosity relative to its source herds, possessed no unique and few rare alleles, and the genetic distances between the Pennsylvania herd and its sources were large. Simulations were performed to identify bottleneck scenarios in agreement with levels of variation in the Pennsylvania herd. Our data confirm that the rate of population growth post-relocation may have important genetic consequences and indicate that theoretical predictions regarding the maintenance of genetic variation during relocation events must be viewed with caution when small numbers of a polygynous species are released.

Validation Tests of a Spatially Explicit Habitat Effectiveness Model for Rocky Mountain Elk

We tested the validity of a spatially explicit habitat effectiveness model for Rocky Mountain elk (Cervus elaphus nelsoni). The model scored habitat effectiveness based on seasonal changes in the quality, quantity, and availability of forage. Seasonal forage potential scores were derived by integrating information on existing vegetation, site potential, historic disturbances, topography, and roads. The model generated maps of seasonal habitat effectiveness that were used to create utilization distributions (UD; i.e. 3-dimensional density estimates). We tested the elk habitat model using telemetry data collected on 5 cow elk sub-herds from 1993 to 1997 in Custer State Park (CSP), South Dakota, USA. We computed fixed kernel UD from elk telemetry data and simulated random UD within the confines of each sub-herd boundary. The degree of fit between elk UD and model predicted UD (elk-model UD) and random UD and model predicted UD (random-model UD) was represented by sub-herd, season, and year using the Volume of Intersection test statistic (V.I. Index). There were no differences in V.I. Indices by year for elk-model (1993 = 0.59, 1994 = 0.54, 1995 = 0.60, 1996 = 0.57, 1997 = 0.57; F 4,70 = 0.93, P = 0.45) or random-model (1993 = 0.59, 1994 = 0.55, 1995 = 0.59, 1996 = 0.58, 1997 = 0.59; F 4,70 = 1.49, P = 0.21) UD; thus, V.I. Indices were pooled across years. Two-way analysis of variance indicated that elk-model V.I. Indices did not differ by sub-herd (B = 0.50, Y = 0.58, A = 0.56, S = 0.58, R = 0.63; F 4,12 = 2.68, P = 0.08), season (Spring = 0.55, Summer = 0.55, Fall = 0.60, Winter = 0.58; F 3,12 = 0.80, P = 0.52), or the interaction terms (B Spring = 0.48, B Summer = 0.52, B Fall = 0.52, B Winter = 0.49, Y Spring = 0.60, Y Summer = 0.52, Y Fall = 0.58, Y Winter = 0.62, A Spring = 0.47, A Summer = 0.58, A Fall = 0.64, A Winter = 0.54, S Spring = 0.54, S Summer = 0.49, S Fall = 0.64, S Winter = 0.65, R Spring = 0.70, R Summer 0.64, R Fall = 0.60, R Winter = 0.59; F 12,55 = 1.68, P = 0.10). V.I. Indices for random-model UD did not differ by season (Spring = 0.58, Summer = 0.57, Fall = 0.58, Winter = 0.59; F 3,12 = 0.56, P = 0.65) or interaction term (B Spring = 0.55, B Summer = 0.58, B Fall = 0.56, B Winter = 0.54, Y Spring = 0.57, Y Summer = 0.53, Y Fall = 0.53, Y Winter = 0.57, A Spring = 0.61, A Summer = 0.63, A Fall = 0.63, A Winter = 0.64, S Spring = 0.60, S Summer = 0.49, S Fall = 0.57, S Winter = 0.59, R Spring = 0.59, R Summer 0.60, R Fall = 0.60, R Winter = 0.59; F 12,55 = 1.44, P = 0.17); however, differences were noted among sub-herds (B = 0.56, Y = 0.55, A = 0.63, S = 0.56, R = 0.60; F 4,12 = 4.48, P = 0.02). V.I. Indices for elk-model UD differed from random-model UD (F 4,12 = 4.71, P = 0.02); model performance was worse than random (i.e., lower V.I. Indices) for 2 sub-herds (elk-model sub-herd B = 0.50 vs. random-mode sub-herd B = 0.56 and elk-model sub-herd A = 0.56 vs. random-model sub-herd A = 0.63). Lower V.I. Indices were observed for 2 sub-herds that occupied areas recently subjected to large-scale wildfires. For sub-herds not subjected to fire effects (i.e., greater loss of vegetation security cover), the model portrayed elk habitat use less consistently, as represented by greater variability (27-42% larger standard errors) in V.I. Indices, during summer. Conversely, the model portrayed elk habitat use most consistent for the same 3 sub-herds during fall.

Genetic variation within and relatedness among wood and plains bison populations

There are two recognized subspecies of bison, wood (Bison bison athabascae) and plains (Bison bison bison) bison. The establishment of most bison populations from a small number of individuals has raised concerns about their genetic variation. To this end, 11 bison populations were surveyed with 11 microsatellite loci in order to calculate genetic variation and genetic distances. Mean number of alleles ranged between 3.18 at Antelope Island State Park (Utah) and 6.55 at Wood Buffalo National Park (Alberta and Northwest Territories). Mean heterozygosity ranged from 0.295 at Antelope Island State Park to 0.669 at Custer State Park (South Dakota). The amount of genetic variability present in the bison populations as measured by mean number of alleles and overall probability of identity was found to correlate with the number of founders for all sampled populations. The G-test for heterogeneity revealed some evidence for the existence of subpopulations at Wood Buffalo National Park, however very small genetic distances between these subpopulations suggest that nuclear material from the plains bison introduced into Wood Buffalo National Park has diffused throughout the park. Genetic distances between the sampled populations were generally larger between than within the two bison subspecies.

THE APPLICATION OF DISCRETE CHOICE MODELS TO WILDLIFE RESOURCE SELECTION STUDIES

This paper introduces the theory and application of discrete choice models to resource selection studies. Discrete choice models calculate the probability of an individual selecting a resource as a function of the attributes of that resource and all other available resources. The data for these attributes may be continuous or categorical. When availability is the same for all individuals and only two resources are available, the multinomial logit discrete choice model reduces to the logistic model. Discrete choice models and advances in GIS technology give the researcher flexibility in defining resource availability separately for each individual over time and space. The output of the discrete choice approach also provides managers with a tool to explore the effects of potential management actions and provides researchers with new hypotheses deserving of further investigation. To illustrate the application of discrete choice models to resource selection studies, we present a case study of summer diurnal bed site selection by elk (Cervus elaphus) in Custer State Park, South Dakota, United States. The results demonstrate the importance of factors relating to thermal regulation, hiding cover, and potentially forage, in elk bed site selection in this region.

Genetic variation within and relatedness among wood and plains bison populations

There are two recognized subspecies of bison, wood (Bison bison athabascae) and plains (Bison bison bison) bison. The establishment of most bison populations from a small number of individuals has raised concerns about their genetic variation. To this end, 11 bison populations were surveyed with 11 microsatellite loci in order to calculate genetic variation and genetic distances. Mean number of alleles ranged between 3.18 at Antelope Island State Park (Utah) and 6.55 at Wood Buffalo National Park (Alberta and Northwest Territories). Mean heterozygosity ranged from 0.295 at Antelope Island State Park to 0.669 at Custer State Park (South Dakota). The amount of genetic variability present in the bison populations as measured by mean number of alleles and overall probability of identity was found to correlate with the number of founders for all sampled populations. The G-test for heterogeneity revealed some evidence for the existence of subpopulations at Wood Buffalo National Park, however very small genetic distances between these subpopulations suggest that nuclear material from the plains bison introduced into Wood Buffalo National Park has diffused throughout the park. Genetic distances between the sampled populations were generally larger between than within the two bison subspecies.Key words: Bison bison bison, Bison bison athabascae, DNA microsatellites, genetic variation, genetic relatedness.

Summer Bed Sites of Elk (Cervus elaphus) in the Black Hills, South Dakota: Considerations for Thermal Cover Management

Abstract We characterized 131 summer, diurnal bed sites of 26 elk (11 bulls and 15 cows) in Custer State Park, South Dakota, from 5 June–30 August 1994, 1995 and 1996. Overstory canopy closure, number and basal area of trees, percent litter and bare ground were greater (P 0.05). Trees were present at 128/131 (97.7%) of bed sites (0.01 ha square plot), but occurred on only 41.2% (54/131) of random plots. An average summer, diurnal elk bed site had basal area >12.4 m2/ha, >110 trees/ha, >54% canopy closure on N aspects. Overstory canopy closure, tree basal area and microsite temperature correctl...

Bovine mtDNA Discovered in North American Bison Populations

North American bison (Bison bison), which once numbered in the millions, were nearly extirpated by the late 1800s. The present recovery of the bison is owed to ranchers who collected bison scattered across the prairies for the purpose of establishing founding stocks (Allen 1877; Garretson 1934; Rorabacher 1970; Dary 1974; Ogilvie 1979). By 1889 there were an estimated 200 bison in Yellowstone National Park, Wyoming, 550 bison in Wood Buffalo National Park (Alberta and Northwest Territories; WBNP), and only 340 bison held on private ranches and wild herds (Jenning & Hebbing 1983). By the 1900s the bison population in Yellowstone and WBNP had dropped to 22 and 250 animals, respectively, because of poaching. Bison used to restock parks in both the United States and Canada were selected from the small surviving nucleus of animals. Today bison populations are flourishing, and more than 18,696 bison can be found in the North American parks alone (Walker 1993). Consequently, conservation efforts have moved from increasing bison numbers to accumulating information on the genetic diversity and relatedness of populations. In the process of constructing a phylogeny for North American bison from mitochondrial DNA (mtDNA), we discovered a bovine (Bos taurus) haplotype (mitochondrial genotype) in the Custer State Park (CSP) herd of South Dakota. The discovery of the bovine haplotype prompted a survey for bovine haplotypes among eight other park populations of bison. Because bison were exchanged between several established park populations, the possibility exists that bovine genes have spread throughout North American bison populations. Park populations that did not ex-

Immobilization of Rocky Mountain elk with Telazol and xylazine hydrochloride, and antagonism by yohimbine hydrochloride.

Ten trapped Rocky Mountain elk (Cervus elaphus nelsoni) were successfully immobilized with a combination of 500 mg Telazol and 60 mg xylazine hydrochloride (HCl) from 9 July to 25 August 1993 in Custer State Park, South Dakota (USA). Mean (SD) dosages of 2.5 (0.6) mg/kg Telazol and 0.3 (0.1) mg/kg xylazine HCl, respectively, were administered, resulting in a mean (SD) induction time of 4.6 (0.8) min. Induction time varied with weight and dosage. Respiratory rate (breaths/min) increased following injection of Telazol and xylazine HCl and remained elevated or continued to increase through 10 min post-injection and then declined. There were no mortalities in this study. Forty mg of yohimbine HCl was used as an antagonist in eight elk, resulting in a mean (SD) recovery time of 14.0 (9.9) min when administered intravenously (n = 6), and 124.7 (9.5) min when given intramuscularly (n = 2). Recovery time varied with weight and dosage of yohimbine. Elk given 2.1 to 2.6 mg/kg Telazol and 0.1 to 0.3 mg/kg xylazine HCl responded to yohimbine HCl when administered intravenously.

Early Pregnancy Determination Using Serum Progesterone Concentration in Bighorn Sheep

We determined serum progesterone concentrations of 25 female bighorn sheep (Ovis canadensis) in February 1984 and January 1985 as an indicator of pregnancy. Accuracy in predicting pregnancy was 90% in 1984, 80% in 1985, and 84% over both years. Most misclassifications were attributed to sampling too close to estrous. Accuracy may be improved if sampling occurs >16 days after the conclusion of breeding activity. Serum progesterone concentration is an accurate indicator of early pregnancy in bighorn sheep. J. WILDL. MANAGE. 52(4):610-612 Detection of pregnancy early in gestation is required to accurately determine reproductive rates and estimate early prenatal loss. Several techniques are used for pregnancy determination of domestic animals; some have been used successfully for wild animals (e.g., rectal palpation [Greer and Hawkins 1967, Follis and Spillet 1974], laparotomy [Zwank 1981], ultrasound [Smith and Lindzey 1982, Harper and Cohen 1985], and hormonal assay [Ramsay and Sadleir 1979, Whitehead and McEwan 1980]). Blood progesterone concentrations have been shown to be accurate indicators of pregnancy in domestic (Bassett et al. 1969) and bighorn females (Ramsay and Sadleir 1979, Whitehead and McEwan 1980). Progesterone determination has the advantage of relatively simple sample collection (if animals can be trapped and handled) and relatively inexpensive analysis. Our study was designed to determine if progesterone serum concentrations indicated early pregnancy in free-ranging bighorn sheep. Serum progesterone concentrations were assayed by B. Pettitjean (Anim. Sci. Dep., South Dakota State Univ.). We thank Custer State Park (CSP) personnel and students from South Dakota State University for assistance with trapping. Funding was provided by a grant from the Foundation for North American Wild Sheep, Custer State Park, and federal aid administered by South Dakota Department of Game, Fish and Parks.

Cranial Characters of a Dog-Coyote Hybrid

In April, 1941, as my wife and I were driving eastward through the Black Hills of South Dakota, we visited the zoo in Custer State Park and examined the ca'ged animals there. One canid was of a kind unknown to me; as it stood far back in its cage facing us a red ruff of hair on its chest and lower neck was prominent. A ten year old boy who chanced by on his bicycle informed me that this creature was a cross between a caged female coyote and the boy's wire-haired fox terrier. Written request for the skull of the hybrid when it died resulted in receipt of the skull on January 21, 1942. In a letter dated February 16, 1942, E. L. Burns wrote that the hybrid was approximately 10 months old when it died and the offspring of a female coyote 3 years old and a wire-haired fox terrier 5 years old.