Bighorn lamb mortality: predation, inbreeding, and population effects

1989 ◽  
Vol 67 (3) ◽  
pp. 699-705 ◽  
Author(s):  
Christine C. Hass
Keyword(s):  
Inbreeding Depression ◽  
High Mortality ◽  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Inbreeding Coefficients ◽  
Population Effects ◽  
Population Numbers

Survival of lambs in the population of bighorn sheep (Ovis canadensis) on the National Bison Range, Montana, was less than 25% during 1983 and 1984. Sixty-seven percent of lamb mortality occurred within 3 days of birth; ewe behaviour and recovered remains indicated that coyotes likely accounted for most of the mortality. Herd history, calculated inbreeding coefficients, and the observation of several small, weak lambs implied that inbreeding depression, while probably not a major factor in lamb mortality, may have predisposed some lambs to predation. Lamb production was high (88–96%); in spite of high mortality, population numbers were stable.

Ecological correlates of pneumonia epizootics in bighorn sheep herds

2001 ◽  
Vol 79 (8) ◽  
pp. 1423-1432 ◽  
Author(s):  
Ryan J Monello ◽  
Dennis L Murray ◽  
E Frances Cassirer
Keyword(s):  
Horizontal Transmission ◽  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Domestic Sheep ◽  
Population Declines ◽  
Density Dependent ◽  
Temperature Regimes ◽  
Reservoir Hosts ◽  
The Relationship ◽  
Population Numbers

Bighorn sheep (Ovis canadensis) populations commonly experience pneumonia outbreaks caused by Pasteurella spp. that result in a partial or complete dieoff. Although several factors can contribute to Pasteurella spp. transmission or infectivity in bighorn sheep, to date the importance of such factors in population declines has not been rigorously examined. We evaluated the relationship between pneumonia-induced dieoffs in bighorn sheep and environmental and biological factors by analyzing demographic information for 99 herds across the species' geographic range. Our analysis revealed that 88% of pneumonia-induced dieoffs occurred at or within 3 years of peak population numbers, which implies that density-dependent forces such as food shortage or stress contribute to bighorns' susceptibility to pneumonia. There were few differences in the growth rates of dieoff and non-dieoff populations, suggesting that pneumonia did not manifest itself demographically prior to an outbreak. On average, abundance of lambs was most dramatically reduced post outbreak (–66%) relative to that of either rams (–35%) or ewes (–42%). Deviations in normal precipitation and temperature regimes were not associated with the onset of pneumonia outbreaks, but herds found in proximity to domestic sheep tended to be more susceptible to dieoff. Our results suggest that bighorn sheep herds are rendered vulnerable to pneumonia principally through density-dependent factors, as well as through horizontal transmission of Pasteurella spp. from domestic sheep serving as reservoir hosts.

scholarly journals Brucellosis in Captive Rocky Mountain Bighorn Sheep (Ovis canadensis) Caused by Brucella abortus Biovar 4

2004 ◽  
Vol 40 (2) ◽  
pp. 311-315 ◽  
Author(s):  
Terry J. Kreeger ◽  
Walter E. Cook ◽  
William H. Edwards ◽  
Todd Cornish
Keyword(s):  
Brucella Abortus ◽  
Rocky Mountain ◽  
Bighorn Sheep ◽  
Ovis Canadensis

scholarly journals Desert Bighorn Sheep: Changes in Genetic Variation Over Time and the Impact of Merging Populations

2014 ◽  
Vol 5 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Philip W. Hedrick ◽  
John D. Wehausen
Keyword(s):  
Genetic Variation ◽  
New Mexico ◽  
Monitoring And Evaluation ◽  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Mexican Population ◽  
Desert Bighorn Sheep ◽  
Two Generations ◽  
The Impact ◽  
Over Time

Abstract Founder effects, genetic bottlenecks, and genetic drift in general can lead to low levels of genetic diversity, which can influence the persistence of populations. We examine genetic variation in two populations of desert bighorn sheep Ovis canadensis from New Mexico and Mexico to measure change over time and evaluate the impact of introducing individuals from one population into the other. Over about three generations, the amount of genetic variation in the New Mexico population increased. In contrast, over about two generations the amount of genetic variation in the Mexican population decreased by a great extent compared with an estimate from another Mexican population from which it is primarily descended. The potential reasons for these changes are discussed. In addition, although both populations have low genetic variation, introduction of Mexican rams into the New Mexico population might increase the amount of genetic variation in the New Mexico population. Overall, it appears that management to increase genetic variation might require substantial detailed monitoring and evaluation of ancestry from the different sources and fitness components.

scholarly journals Effects of inbreeding on number of piglets born total, born alive and weaned in Austrian Large White and Landrace pigs

2009 ◽  
Vol 52 (1) ◽  
pp. 51-64 ◽  
Author(s):  
A. Köck ◽  
B. Fürst-Waltl ◽  
R. Baumung
Keyword(s):  
Inbreeding Depression ◽  
Reproductive Performance ◽  
Regression Models ◽  
Inbreeding Coefficient ◽  
Significant Positive Effect ◽  
Weaned Piglets ◽  
Large White ◽  
Inbreeding Coefficients ◽  
Negative Effect ◽  
Positive Effect

Abstract. In this study records of 58 925 litters of Austrian Large White and 17 846 litters of Austrian Landrace pigs were analysed. Regression models were used to determine the effects of litter, dam and sire inbreeding on total number of born, born alive and weaned piglets in Large White and Landrace. In both populations, litter and dam inbreeding showed a negative effect on all traits. Sire inbreeding had no effect in Large White, whereas a significant positive effect was observed in Landrace. On average, inbred sires with an inbreeding coefficient of 10 % had 0.45 more piglets born total and 0.43 more piglets born alive in comparison to non-inbred sires. In a further analysis the total inbreeding coefficients of the animals were divided into two parts: »new« and »old« inbreeding. »New« inbreeding was defined as the period of the first five generations. It was shown that the observed inbreeding effects were not only caused by recent inbreeding. Reproductive performance was also affected by »old« inbreeding. Finally partial inbreeding coefficients of four important ancestors in each population were calculated to investigate if inbreeding effects are similar among these ancestors. The results revealed a varation of inbreeding effects among the four ancestors. Alleles contibuting to inbreeding depression were descendent from specific ancestors.

Factors influencing heart rate in free-ranging bighorn sheep: a physiological approach to the study of wildlife harassment

1979 ◽  
Vol 57 (10) ◽  
pp. 2010-2021 ◽  
Author(s):  
Robert A. MacArthur ◽  
Ronald H. Johnston ◽  
Valerius Geist
Keyword(s):  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Activity Level ◽  
Base Line ◽  
Vehicular Traffic ◽  
Behavioral Reactions ◽  
Factors Influencing ◽  
Close Range ◽  
Physiological Approach ◽  
Free Ranging

The telemetered heart rates (HR) of unrestrained female bighorn sheep (Ovis canadensis canadensis) were recorded under various behavioral and environmental circumstances. In all ewes HR varied positively with activity level and inversely with distance to a road traversing the study area. The HR recorded from animals moving at night or through timber by day were higher than during daytime movement across open slopes.Responses to transient stimuli varied greatly. The appearance of free-ranging canids evoked maximal increases in HR in all ewes. Vehicular traffic and aircraft elicited HR responses only at close range (< 200 m). Most (78.1%) HR responses to disturbing stimuli preceded or occurred in the absence of overt behavioral reactions. The HR usually peaked within 60 s of the onset of the response and recovered to predisturbance base line in less than 200 s. The appearance and continued presence (1–10 min) of a human within 50 m of the sheep resulted in a 20% rise in mean HR. The significance of these findings is discussed in relation to the behavior, ecology, and bioenergetics of bighorn sheep.

scholarly journals Differences in leukocyte differentiation molecule abundances on domestic sheep (Ovis aries) and bighorn sheep (Ovis canadensis) neutrophils identified by flow cytometry

2016 ◽  
Vol 46 ◽  
pp. 40-46 ◽  
Author(s):  
Margaret A. Highland ◽  
David A. Schneider ◽  
Stephen N. White ◽  
Sally A. Madsen-Bouterse ◽  
Donald P. Knowles ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Bighorn Sheep ◽  
Ovis Canadensis ◽  
Ovis Aries ◽  
Domestic Sheep

scholarly journals A multivariate analysis with direct additive and inbreeding depression load effects

2019 ◽  
Vol 51 (1) ◽  
Author(s):  
Luis Varona ◽  
Juan Altarriba ◽  
Carlos Moreno ◽  
María Martínez-Castillero ◽  
Joaquim Casellas
Keyword(s):  
Beef Cattle ◽  
Inbreeding Depression ◽  
Negative Correlation ◽  
Simulated Data ◽  
Genetic Effects ◽  
Strong Negative Correlation ◽  
Additive Variance ◽  
Inbreeding Coefficients ◽  
Load Effects ◽  
Additive Genetic Effects

Abstract Background Inbreeding is caused by mating between related individuals and its most common consequence is inbreeding depression. Several studies have detected heterogeneity in inbreeding depression among founder individuals, and recently a procedure for predicting hidden inbreeding depression loads associated with founders and the Mendelian sampling of non-founders has been developed. The objectives of our study were to expand this model to predict the inbreeding loads for all individuals in the pedigree and to estimate the covariance between the inbreeding loads and the additive genetic effects for the trait of interest. We tested the proposed approach with simulated data and with two datasets of records on weaning weight from the Spanish Pirenaica and Rubia Gallega beef cattle breeds. Results The posterior estimates of the variance components with the simulated datasets did not differ significantly from the simulation parameters. In addition, the correlation between the predicted and simulated inbreeding loads were always positive and ranged from 0.27 to 0.82. The beef cattle datasets comprised 35,126 and 75,194 records on weights between 170 and 250 days of age, and pedigrees of 308,836 and 384,434 individual-sire-dam entries for the Pirenaica and Rubia Gallega breeds, respectively. The posterior mean estimates of the variance of inbreeding depression loads were 29,967.8 and 28,222.4 for the Pirenaica and Rubia Gallega breeds, respectively. They were larger than those of the additive variance (695.0 and 439.8 for Pirenaica and Rubia Gallega, respectively), because they should be understood as the variance of the inbreeding depression achieved by a fully inbred (100%) descendant. Therefore, the inbreeding loads have to be rescaled for smaller inbreeding coefficients. In addition, a strong negative correlation (− 0.43 ± 0.10) between additive effects and inbreeding loads was detected in the Pirenaica, but not in the Rubia Gallega breed. Conclusions The results of the simulation study confirmed the ability of the proposed procedure to predict inbreeding depression loads for all individuals in the populations. Furthermore, the results obtained from the two real datasets confirmed the variability in the inbreeding depression loads in both breeds and suggested a negative correlation of the inbreeding loads with the additive genetic effects in the Pirenaica breed.

scholarly journals Linking population performance to nutritional condition in an alpine ungulate

2020 ◽  
Vol 101 (5) ◽  
pp. 1244-1256 ◽  
Author(s):  
Thomas R Stephenson ◽  
David W German ◽  
E Frances Cassirer ◽  
Daniel P Walsh ◽  
Marcus E Blum ◽  
...  
Keyword(s):  
Body Fat ◽  
Bighorn Sheep ◽  
Nutritional Condition ◽  
Ovis Canadensis ◽  
Population Increase ◽  
Overwinter Survival ◽  
Fat Reserves ◽  
Adult Females ◽  
Free Body

Abstract Bighorn sheep (Ovis canadensis) can live in extremely harsh environments and subsist on submaintenance diets for much of the year. Under these conditions, energy stored as body fat serves as an essential reserve for supplementing dietary intake to meet metabolic demands of survival and reproduction. We developed equations to predict ingesta-free body fat in bighorn sheep using ultrasonography and condition scores in vivo and carcass measurements postmortem. We then used in vivo equations to investigate the relationships between body fat, pregnancy, overwinter survival, and population growth in free-ranging bighorn sheep in California and Nevada. Among 11 subpopulations that included alpine winter residents and migrants, mean ingesta-free body fat of lactating adult females during autumn ranged between 8.8% and 15.0%; mean body fat for nonlactating females ranged from 16.4% to 20.9%. In adult females, ingesta-free body fat &gt; 7.7% during January (early in the second trimester) corresponded with a &gt; 90% probability of pregnancy and ingesta-free body fat &gt; 13.5% during autumn yielded a probability of overwinter survival &gt; 90%. Mean ingesta-free body fat of lactating females in autumn was positively associated with finite rate of population increase (λ) over the subsequent year in bighorn sheep subpopulations that wintered in alpine landscapes. Bighorn sheep with ingesta-free body fat of 26% in autumn and living in alpine environments possess energy reserves sufficient to meet resting metabolism for 83 days on fat reserves alone. We demonstrated that nutritional condition can be a pervasive mechanism underlying demography in bighorn sheep and characterizes the nutritional value of their occupied ranges. Mountain sheep are capital survivors in addition to being capital breeders, and because they inhabit landscapes with extreme seasonal forage scarcity, they also can be fat reserve obligates. Quantifying nutritional condition is essential for understanding the quality of habitats, how it underpins demography, and the proximity of a population to a nutritional threshold.

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