Ovis Dalli Research Articles

Spatial overlap of Dall sheep, grizzly bears and wolves in the Richardson Mountains, Canada

Spatial overlap of Dall sheep, grizzly bears and wolves in the Richardson Mountains, Canada

Predator‐Mediated Indirect Effects of Snowshoe Hares on Dall's Sheep in Alaska

ABSTRACTIndirect interactions among species can strongly influence population dynamics and community structure but are often overlooked in management of large mammals. We estimated survival of Dall's sheep (Ovis dalli) in the central Alaska Range, USA, during years of differing snowshoe hare (Lepus americanus) abundance to test whether indirect interactions with a cyclic hare population affect Dall's sheep either negatively, by subsidizing predators (apparent competition), or positively, by diverting predation (apparent commensalism). Annual survival of adult female sheep was consistently high (0.85 for all yr and age classes combined). In contrast, annual estimates of lamb survival ranged from 0.15 to 0.63. The main predators of lambs were coyotes (Canis latrans) and golden eagles (Aquila chrysaetos), which rely on hares as their primary food and prey on lambs secondarily. Coyotes and eagles killed 78% of 65 radiocollared lambs for which cause of death was known. Lamb survival was negatively related to hare abundance during the previous year, and lamb survival rates more than doubled when hare abundance declined, supporting the hypothesis of predator‐mediated apparent competition between hares and sheep. However, stage‐specific predation and delays in predator responses to changes in hare numbers led to a positive relationship between abundance of adult Dall's sheep and hares. Lacking reliable estimates of survival, a manager might erroneously conclude that hares benefit sheep. Thus, support for different indirect effects can be obtained from different types of data, which demonstrates the need to determine the mechanisms that create indirect interactions. Long‐term survey data suggest that predation by coyotes is limiting this sheep population below levels typical when coyotes were rare or absent. Understanding the nature of indirect interactions is necessary to effectively manage complex predator–prey communities.

A genome‐wide set of SNPs detects population substructure and long range linkage disequilibrium in wild sheep

The development of genomic resources for wild species is still in its infancy. However, cross-species utilization of technologies developed for their domestic counterparts has the potential to unlock the genomes of organisms that currently lack genomic resources. Here, we apply the OvineSNP50 BeadChip, developed for domestic sheep, to two related wild ungulate species: the bighorn sheep (Ovis canadensis) and the thinhorn sheep (Ovis dalli). Over 95% of the domestic sheep markers were successfully genotyped in a sample of fifty-two bighorn sheep while over 90% were genotyped in two thinhorn sheep. Pooling the results from both species identified 868 single-nucleotide polymorphisms (SNPs), 570 were detected in bighorn sheep, while 330 SNPs were identified in thinhorn sheep. The total panel of SNPs was able to discriminate between the two species, assign population of origin for bighorn sheep and detect known relationship classes within one population of bighorn sheep. Using an informative subset of these SNPs (n=308), we examined the extent of genome-wide linkage disequilibrium (LD) within one population of bighorn sheep and found that high levels of LD persist over 4 Mb.

Recent Mammals of Alaska S. O. MacDonald , J. A. Cook . 2009. Recent Mammals of Alaska. University of Alaska Press. Fairbanks, Alaska. 387 pp. ISBN: 978-1-60223-047-7. price (hardbound: alkaline paper), $55.00.

S. O. MacDonald, J. A. Cook.2009.Recent Mammals of Alaska. University of Alaska Press, Fairbanks, Alaska, 387 pp. ISBN 978-1-60223-047-7, price (hardbound: alkaline paper), $55.00. Alaska is more than twice the size of Texas and has more than 10,000 km of coastline (the distance from Laramie, Wyoming, to Buenos Aires, Argentina). It is not only a vast land but also a difficult one in which to work during much of the year. Notable mammalogists, from C. Hart Merriam and Joseph Grinnell—the founders of mammalogy—to the authors and their students (many of whom are pictured in this book), have worked diligently to clarify the fauna of this northernmost state, a last redoubt for much of the American megafauna. The book begins with a nice overview of the history of Alaska's mammal collectors and scientific expeditions. These were heroic efforts in the early days of exploration. On an early expedition Major Robert Kennicott died of heart failure while exploring the Yukon in 1866 (the Kennicott Glacier, Kennicott Valley, and Kennicott River are named in his honor). Kennicott was replaced by William Healey Dall (who first observed white sheep on Mt. McKinley, a species that would subsequently be named the Dall Sheep, Ovis dalli , when it was formally described by Nelson in 1884). Dall (who was a student of the Harvard anatomist and mammalogist, Jeffries Wyman, the father of forensic anthropology) had been exploring Siberia when he learned of Kennicott's death, and he left his Siberian expedition and moved to the Yukon River to continue the exploration of that area. The U.S. Biological Survey played a major role in sampling Alaska's mammal fauna, from E. W. Nelson (when he was a private in the Army) to Frederick True, C. Hart Merriam, A. K. Fisher, W. H. Osgood, N. Hollister, and O. Murie (the book is dedicated to Olaus and Margaret Murie). Also making appearances as field collectors are V. H. Cahalane, A. Murie (brother of Olaus and …

The role of phenotypic plasticity in responses of hunted thinhorn sheep ram horn growth to changing climate conditions

When phenotypic change occurs over time in wildlife populations, it can be difficult to determine to what degree it is because of genetic effects or phenotypic plasticity. Here, we assess phenotypic changes over time in horn length and volume of thinhorn sheep (Ovis dalli) rams from Yukon Territory, Canada. We considered 42 years of horn growth from over 50,000 growth measurements in over 8000 individuals. We found that weather explained a large proportion of the annual fluctuation in horn growth, being particularly sensitive to spring weather. Only 2.5% of variance in horn length growth could be explained by an individual effect, and thus any genetic changes over the time period could only have had a small effect on phenotypes. Our findings allow insight into the capacity for horn morphology to react to selection pressures and demonstrate the overall importance of climate in determining growth.

Zur Haltung von Dallschafen ( Ovis dalli) im Zoologischen Garten Leipzig : Keeping Dall's Sheep ( Ovis dalli) at Leipzig Zoo

Keeping and breeding Dall's Sheep ( Ovis dalli) in Leipzig Zoo between 1982 and 2009 are reflected and analysed. Seven animals were brought into the collection. 60 specimens were kept so far. The species hast turned out to be difficult in Middle-Europe‘s climate but nevertheless is manageable and reproductive. The rearing rate (animals have reached at least the age of 1 year) is 40%. Remarkable veterinarian treatments for keeping the stock healthy and especially for ensuring the breeding are described. For sure, deep engagement of keepers, veterinarians and curators is needed to keep this species successfully. Hopefully a lot of colleagues will take this as a challenge to increase numbers in Europe by joining the group of holders of this splendid wild sheep.

Re‐sequencing regions of the ovine Y chromosome in domestic and wild sheep reveals novel paternal haplotypes

The male-specific region of the ovine Y chromosome (MSY) remains poorly characterized, yet sequence variants from this region have the potential to reveal the wild progenitor of domestic sheep or examples of domestic and wild paternal introgression. The 5' promoter region of the sex-determining gene SRY was re-sequenced using a subset of wild sheep including bighorn (Ovis canadensis), thinhorn (Ovis dalli spp.), urial (Ovis vignei), argali (Ovis ammon), mouflon (Ovis musimon) and domestic sheep (Ovis aries). Seven novel SNPs (oY2-oY8) were revealed; these were polymorphic between but not within species. Re-sequencing and fragment analysis was applied to the MSY microsatellite SRYM18. It contains a complex compound repeat structure and sequencing of three novel size fragments revealed that a pentanucleotide element remained fixed, whilst a dinucleotide element displayed variability within species. Comparison of the sequence between species revealed that urial and argali sheep grouped more closely to the mouflon and domestic breeds than the pachyceriforms (bighorn and thinhorn). SNP and microsatellite data were combined to define six previously undetected haplotypes. Analysis revealed the mouflon as the only species to share a haplotype with domestic sheep, consistent with its status as a feral domesticate that has undergone male-mediated exchange with domestic animals. A comparison of the remaining wild species and domestic sheep revealed that O. aries is free from signatures of wild sheep introgression.

Bilateral Perirenal Hemorrhage in two Stone's Sheep (Ovis Dalli Stonei): A Possible Manifestation of Malignant Catarrhal Fever

Malignant catarrhal fever (MCF)-like disease was diagnosed at postmortem in 2 Stone's sheep (Ovis dalli stonei). On gross examination, the predominant abnormality in both sheep was severe perirenal hemorrhage and multiple renal infarcts. Microscopically, there was severe, multisystemic lymphocytic arteritis. Both sheep were positive for Ovine herpesvirus 2 (OvHV-2) on polymerase chain reaction, and partial sequencing of the viral DNA polymerase genes from the 2 sheep revealed >99% homology, with 96% similarity to the reference GenBank OvHV-2 viral sequence. Based on the histological lesions, polymerase chain reaction results, and viral DNA polymerase gene sequencing, a diagnosis of OvHV-2-mediated MCF was made. Massive perirenal hemorrhage has not been described previously as a manifestation of MCF.

Coat darkness is associated with social dominance and mating behaviour in a mountain sheep hybrid lineage

Natural hybridization can produce novel traits when morphologically different populations hybridize, and can introduce variation in traits that become associated with sexual selection. Evidence from breeding experiments and genetic markers indicate that the great variation in coat darkness and the unique coat patterns found in Stone's sheep Ovis dalli stonei , populations, have resulted from an ancient hybridization event between thinhorn sheep, O. dalli, and bighorn sheep, O. canadensis . Behavioural evidence gathered in 2003 and 2004 in Yukon Territory, Canada, showed that higher dominance rank was correlated with increasing darkness in rams, and comparatively darker rams were seen more often tending oestrous ewes. The relationship between ram darkness and dominance and use of the tending mating tactic was still significant after age or horn size were controlled. In sum, our study demonstrates an interesting example of the potential for hybridization to generate diversity. In the case of mountain sheep an ancestral hybridization has resulted in a subspecies with unique coat colour characteristics that are associated with social dominance and mating behaviour.

Use of Natural Licks by Four Species of Ungulates in Northern British Columbia

Use of licks influences the movements and distribution of ungulates. We recorded attendance patterns, duration of visits to licks, and time spent licking by 4 ungulate species at wet and dry licks to examine possible influences on the timing of use of licks in northern British Columbia, Canada. Within-species licking intensity (based on regressions between time spent licking per visit and duration of visits to licks) was higher for elk (Cervus elaphus) than for moose (Alces alces) at wet licks, and higher for mountain goats (Oreamnos americanus) than for Stone’s sheep (Ovis dalli stonei) at dry licks. Lick response variables (duration of visits to licks, time spent licking per visit, and proportion of time spent licking) did not vary significantly among early, mid-, and late summer seasons, but there were species-specific differences in the timing of highest attendance. High use of wet licks by both female and male elk in late May followed vegetation greening at low elevations. Average attendance by female elk was highest in late June, coinciding with high lactation demands. Attendance by moose at wet licks was highest in mid-July, potentially coinciding with other aspects of forage phenology such as increased plant defensive compounds. Attendance by Stone’s sheep and mountain goats at dry licks was high in early July, following forage change at high elevations and again in early August, potentially related to the tradeoff between lactation demands and predation risk. Across species, consumption of lick soils allows ungulates to improve rumen function and nutrient absorption during the transition to spring and summer forage and to supplement elemental intake by females during the nutritional stress associated with lactation.

ACS In Alaska

RETURN TO ISSUEPREVEditorialNEXTACS In AlaskaRUDY M. BAUMCite this: Chem. Eng. News 2008, 86, 30, 5Publication Date (Print):July 28, 2008Publication History Published online14 November 2010Published inissue 28 July 2008https://doi.org/10.1021/cen-v086n030.p005Copyright © 2008 AMERICAN CHEMICAL SOCIETYArticle Views62Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (131 KB) Get e-Alerts

MC1R variants correlate with thinhorn sheep colour cline but not individual colour

The melanocortin 1 receptor (MC1R) gene has provided a window on the evolution of colour polymorphisms. Recent studies have demonstrated associations between MC1R and melanism in a number of wildlife species. Thinhorn sheep ( Ovis dalli Nelson, 1884) are a possible species to test for association between MC1R polymorphisms and melanism. Across their range the pelage colour of thinhorn sheep intergrades between all white phenotypes to very dark phenotypes. Most thinhorn sheep are white; however, there is a 1200 km cline from light to dark sheep that occurs over three genetically distinct polymorphic populations. We sequenced the entire MC1R gene from 40 individuals across the range of thinhorn sheep. We found a single nucleotide polymorphism in MC1R at base pair position 921 that coincided with the geographic cline. However, at the individual level we found no relationship between individual melanism and genotype.

Linking foraging behavior to population density: An assessment of GMM models for Dall sheep

We adapted Owen-Smith's general growth-metabolism-mortality (GMM) model to estimate the abundance of a population of Dall sheep ( Ovis dalli dalli) in the southwest Yukon, Canada. Estimated sheep densities using the GMM approach (18–32 sheep/km 2) approximated long-term aerial survey data (20.2–29.6 sheep/km 2) when biologically realistic levels of parameter variation were introduced. Sheep population growth rate based on the GMM model was most sensitive to the metabolic conversion of forage into sheep biomass, rate of vegetation attrition, and mortality rate during winter. Model estimates may be improved with better estimates of metabolic conversion of forage into sheep body mass, vegetation attrition, incorporation of inter-annual variability, and stratification by sex and age classes. Overall, GMM models using mechanistic physiological and behavioral information may provide a complimentary approach to aerial censuses for estimating ungulate population abundance.

PROTOSTRONGYLID PARASITES AND PNEUMONIA IN CAPTIVE AND WILD THINHORN SHEEP (OVIS DALLI)

We describe health significance of protostrongylid parasites (Parelaphostrongylus odocoilei and Protostrongylus stilesi) and other respiratory pathogens in more than 50 naturally infected Dall's sheep (Ovis dalli dalli) from the Mackenzie Mountains, Northwest Territories (1998-2002) as well as in three Stone's sheep (O. d. stonei) experimentally infected with P. odocoilei (2000-2002). Histological lesions in the brain and distribution of P. odocoilei in the muscles of experimentally and naturally infected sheep were consistent with a previously hypothesized "central nervous system to muscle" pattern of migration for P. odocoilei. Dimensions of granulomas associated with eggs of P. odocoilei and density of protostrongylid eggs and larvae in the cranial lung correlated with intensity of larvae in feces, and all varied with season of collection. Prevalence of P. stilesi based on the presence of larvae in feces underestimated true prevalence (based on examination of lungs) in wild Dall's sheep collected in summer and fall. Similarly, counts of both types of protostrongylid larvae in feces were unreliable indicators of parasitic infection in wild Dall's sheep with concomitant bacterial pneumonia associated with Arcanobacterium pyogenes, Pasteurella sp., and Mannheimia sp. Diffuse, interstitial pneumonia due to P. odocoilei led to fatal pulmonary hemorrhage and edema after exertion in one experimentally infected Stone's sheep and one naturally infected Dall's sheep. Bacterial and verminous pneumonia associated with pathogens endemic in wild Dall's sheep in the Mackenzie Mountains caused sporadic mortalities. There was no evidence of respiratory viruses or bacterial strains associated with domestic ruminants, from which this population of wild sheep has been historically isolated.

Habitat selection by female Stone's sheep in relation to vegetation, topography, and risk of predation

Stone's sheep (Ovis dalli stonei) are susceptible to anthropogenic disturbances, but few data have been available to help minimize impacts. We used the movements of individuals to define use and availability, and resource-selection functions (RSF) and the information-theoretic approach to examine seasonal habitat selection and interannual variation in selection of attributes by groups of Stone's sheep. Movement rates of Stone's sheep followed consistent yearly patterns, with highest rates occurring in summer and fall. Models that contained vegetation, topography, and risk of predation best explained resource selection. Topographic features ranked better, however, than components of vegetation or risk of predation from grizzly bears (Ursus arctos) and wolves (Canis lupus) at explaining habitat selection. Selection strategies were variable among groups of Stone's sheep and between years within groups even though consistencies in selection for steep slopes, ridge-like topography, south aspects, and upper elevations were common. This research provides the first comprehensive analysis of habitat selection by Stone's sheep, which show strong fidelity to seasonal ranges but also exhibit behavioural plasticity in selection of attributes within those ranges.

Horn growth rate and longevity: implications for natural and artificial selection in thinhorn sheep (Ovis dalli)

We used horn measurements from natural and hunted mortalities of male thinhorn sheep Ovis dalli from Yukon Territory, Canada, to examine the relationship between rapid growth early in life and longevity. We found that rapid growth was associated with reduced longevity for sheep aged 5 years and older for both the hunted and natural mortality data sets. The negative relationship between growth rate and longevity in hunted sheep can at least partially be explained by morphologically biased hunting regulations. The same trend was evident from natural mortalities from populations that were not hunted or underwent very limited hunting, suggesting a naturally imposed mortality cost directly or indirectly associated with rapid growth. Age and growth rate were both positively associated with horn size at death for both data sets, however of the two growth rate appeared to be a better predictor. Large horn size can be achieved both by individuals that grow horns rapidly and by those that have greater longevity, and the trade-off between growth rate and longevity could limit horn size evolution in this species. The similarity in the relationship between growth rate and longevity for hunted and natural mortalities suggests that horn growth rate should not respond to artificial selection. Our study highlights the need for the existence and study of protected populations to properly assess the impacts of selective harvesting.

Bighorn Sheep Selection of Landscape Features in an Active Copper Mine

Bighorn sheep (Ovis canadensis) and Dall's sheep (O. dalli) use mining areas despite high human activity. We studied bighorn sheep selection of landscape features within a mine in a desert environment to determine those important for bighorn sheep and to enhance reclamation efforts of mines in desert environments. We collared and observed 8 male and 6 female bighorn sheep from December 2003 to January 2005 in the Silver Bell Mountains, Arizona, USA. We classified 13 unique features within a mine landscape based on topography, hydrology, and vegetation. Subadult male, adult male, and female bighorn sheep used desert islands (54, 76, and 54%, respectively) followed by highwalls (14, <10, and 11%, respectively). Subadult male, adult male, and female bighorn sheep selected for desert islands, and subadult males and females also selected for highwalls, whereas adult males did not. We did not observe bighorn sheep using leach ponds, pit bottoms, or tailings dumps. Bighorn sheep behavior while on desert islands was similar to behavior recorded when outside the mine perimeter. Subadult male and female bighorn sheep fed and were alert less and socially interacted more on highwalls than they did while outside the mine perimeter. Bighorn sheep in mines select areas similar to conspecifics outside of mined areas. In areas where mining and bighorn sheep are in proximity, mining engineers and wildlife biologists should work together to design reclamation plans that benefit bighorn sheep. In places where revegetation is difficult (i.e., deserts), mine engineers should design infrastructure (i.e., roadways, waste dumps, buildings) to minimize the unnecessary destruction of native slopes and vegetation.

Evaluation of Aerial Survey Methods for Dall's Sheep

Abstract Most Dall's sheep (Ovis dalli dalli) population-monitoring efforts use intensive aerial surveys with no attempt to estimate variance or adjust for potential sightability bias. We used radiocollared sheep to assess factors that could affect sightability of Dall's sheep in standard fixed-wing and helicopter surveys and to evaluate feasibility of methods that might account for sightability bias. Work was conducted in conjunction with annual aerial surveys of Dall's sheep in the western Baird Mountains, Alaska, USA, in 2000–2003. Overall sightability was relatively high compared with other aerial wildlife surveys, with 88% of the available, marked sheep detected in our fixed-wing surveys. Total counts from helicopter surveys were not consistently larger than counts from fixed-wing surveys of the same units, and detection probabilities did not differ for the 2 aircraft types. Our results suggest that total counts from helicopter surveys cannot be used to obtain reliable estimates of detection probabil...

CHEMICAL COMPOSITION OF LICK SOILS: FUNCTIONS OF SOIL INGESTION BY FOUR UNGULATE SPECIES

Perspectives on the importance of natural salt licks to ungulates have been broadened beyond the role of providing sodium. This study examined the chemical compositions of wet and dry licks in north-central British Columbia, and defined the benefits of licks to elk (Cervus elaphus), moose (Alces alces), Stone’s sheep (Ovis dalli stonei), and mountain goats (Oreamnos americanus). We analyzed soils for buffering compounds (carbonates) and estimated available elements from extractions with solutions at a low, digestive-tract pH. Even though the 2 types of licks are visually distinct, with different concentrations of chemical components, they serve similar functions as concentrated sources of sodium, carbonates, magnesium, and sulfate. Sodium and sulfate concentrations were typically higher at both wet and dry licks than control sites. Carbonates and magnesium were elevated in soils from dry licks and magnesium also was high in inflow waters to wet licks. We estimated elemental intake by ungulates from the composition of forage samples. Forages used by all 4 ungulate species were too low in sodium to meet requirements. Spring and summer forages contained high potassium levels. Licks in our study, therefore, provide ungulates with supplemental sources of sodium that are particularly beneficial to offset increasing demands during lactation and with carbonates to help stabilize rumen pH after forage changes in spring. Supplemental sources of magnesium may be actively sought by ungulates when high levels of dietary potassium affect absorption. To assess the importance of clay in soils ingested at licks, we determined the clay mineral types at licks and compared the buffering capacity of clay-filled fecal material collected at licks with fecal material collected away from licks. Further studies are needed to define the roles of clay in improving forage palatability and digestibility.

THE SEROLOGIC PREVALENCE OF Q FEVER (COXIELLA BURNETII) COMPLEMENT-FIXING ANTIBODIES IN THE PENINSULAR BIGHORN SHEEP OF SOUTHERN CALIFORNIA

Q fever is a rare illness in the Southern California desert. During the past 34 years only 6 patients have been diagnosed with the disease at the Eisenhower Medical Center, a referral center for much of the desert and surrounding mountains. In all but 2 instances, Q fever was identified in patients who have been in contact with imported domestic sheep who are brought to the desert to graze and lamb in the fall and winter. The sheep are sent back to Idaho, Wyoming, and Montana in the spring. With frequent infection by Coxiella burnetii established in domestic sheep, we elected to study the prevalence of complement fixing antibodies to Coxiella burnetii in native bighorn sheep who reside in the lower levels of the mountains surrounding the desert. From 1992 to 1999, of 268 serum samples drawn from male and female lambs and adult sheep, 27 tested positive (10%), which is strikingly low when compared with Dall sheep in Alaska (12 of 15), kangaroos, wild rabbits, and brown rats. Because changes have been made in Peninsular bighorn sheep habitat since the animals were listed as endangered in 1998, further follow-up in Q fever serology testing will be of interest.