Publications

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survey of toxoplasma antibodies among sheep in western united states.a survey was conducted to determine the prevalence of toxoplasma antibodies among breeding ewes and among lambs slaughtered for food in western united states. each serum was tested by the indirect hemaglutination method, using microtiter technique. agglutination (greater than or equal to 2 +) at the 1:64 dilution was considered to be a positive reaction. of 2,164 ewes from 18 flocks tested in california, 523 (24%) were seropositive for toxoplasma gondii, with prevalence rates among flocks rangin ...1977604325
survey of chronic sinusitis-induced skull anomalies in desert bighorn sheep.bone anomalies were found in 20% of 630 skulls from desert bighorn sheep (ovis canadensis) representing populations of california bighorn (o canadensis californiana), lower california bighorn (o canadensis cremnobates), mexican bighorn (o canadensis mexicana), and nelson bighorn (o canadensis nelsoni) that are native to arizona, california, nevada, new mexico, and utah. the anomalies were extremely diverse, ranging from osteonecrosis within the matrix of the paranasal sinuses to extensive lysis ...19817327996
the distribution of dermacentor hunteri and anaplasma sp. in desert bighorn sheep (ovis canadensis).the ixodid tick dermacentor hunteri has been collected intermittently this century, primarily from desert bighorn sheep (ovis canadensis). anaplasma spp. are intraerythrocytic rickettsial parasites of ungulates and are vectored in the western united states by ticks of the genus dermacentor. we tested the hypotheses that d. hunteri would be found infesting all populations of desert bighorn, and that all infested populations would be seropositive for anaplasma sp. dermacentor hunteri was found on ...19979057693
seroprevalence of toxoplasma gondii in rocky mountain bighorn sheep (ovis canadensis).serum samples from 697 rocky mountain bighorn sheep (ovis canadensis) from north america were examined for antibodies to toxoplasma gondii by the modified agglutination test incorporating mercaptoethanol and formalin-fixed tachyzoites. antibodies to t. gondii were found in 25 of 697 (3.6%) sheep in titers of 1:25 (8 sheep), 1:50 (4 sheep), 1:100 (7 sheep), 1:200 (1 sheep), 1:400 (1 sheep), 1:800 (1 sheep), and 1:1,600 (3 sheep). this is the first record of t. gondii exposure in bighorn sheep.200010864265
scientists implicated in atom test deception.described here are the circumstances leading to a recent court ruling that atomic energy commission officials suppressed data indicating a link between two 1953 atomic bomb tests in nevada and sheep deaths in neighboring utah, and then pressured scientific investigators to concur with the aec position. in a 1956 trial, a federal judge denied compensation to the sheep owners. evidence of the deception came to light in 1979 and 1980 and, on 24 august 1982, the same judge ordered a new trial, rul ...198211643806
ecology of bacillary hemoglobinuria. 196414126858
coliform bacteria in sierra nevada wilderness lakes and streams: what is the impact of backpackers, pack animals, and cattle?the presence of coliform bacteria indicates a watershed risk for harboring microbes capable of causing human disease. we hypothesized that water from watersheds that have different human- or animal-use patterns would have differing risks for the presence of coliform bacteria. methods; water was collected in wilderness areas of the sierra nevada range in california. a total of 60 sites from lakes or streams were selected to statistically differentiate the risk categories: 1) high use by backpacke ...200616538940
risk factors for coliform bacteria in backcountry lakes and streams in the sierra nevada mountains: a 5-year study.to provide a 5-year longitudinal assessment of risk of acquiring disease from sierra nevada wilderness area lakes and streams. this study examines the relative risk factors for harmful water microorganisms, using coliforms as an indicator.200818513116
backpacking in yosemite and kings canyon national parks and neighboring wilderness areas: how safe is the water to drink?the objective of this study was to determine the risk of acquiring disease from popular sierra nevada wilderness area lakes and streams. this study examines the relative risk factors for harmful waterborne microorganisms using coliforms as an indicator.200818666919
an ecologic study comparing distribution of pasteurella trehalosi and mannheimia haemolytica between sierra nevada bighorn sheep, white mountain bighorn sheep, and domestic sheep.the prevalence and phenotypic variability of pasteurella and mannheimia isolates from sierra nevada bighorn sheep (ovis canadensis sierrae), white mountain bighorn sheep (ovis canadensis nelsoni), and domestic sheep (ovis aries) from california, usa, were compared. the white mountain bighorn sheep population had a recent history of pneumonia-associated mortality, whereas the sierra nevada bighorn sheep population had no recent history of pneumonia-associated mortality. the domestic sheep flocks ...200919901369
population-specific vital rate contributions influence management of an endangered ungulate.to develop effective management strategies for the recovery of threatened and endangered species, it is critical to identify those vital rates (survival and reproductive parameters) responsible for poor population performance and those whose increase will most efficiently change a population's trajectory. in actual application, however, approaches identifying key vital rates are often limited by inadequate demographic data, by unrealistic assumptions of asymptotic population dynamics, and of equ ...201020945773
Translating effects of inbreeding depression on component vital rates to overall population growth in endangered bighorn sheep.Evidence of inbreeding depression is commonly detected from the fitness traits of animals, yet its effects on population growth rates of endangered species are rarely assessed. We examined whether inbreeding depression was affecting Sierra Nevada bighorn sheep (Ovis canadensis sierrae), a subspecies listed as endangered under the U.S. Endangered Species Act. Our objectives were to characterize genetic variation in this subspecies; test whether inbreeding depression affects bighorn sheep vital ra ...201122070275
pasteurella spp. in sympatric bighorn and domestic sheep.domestic sheep were sighted at different times from 1991 to 1993 on four nevada (usa) ranges occupied by bighorn sheep. nasal and pharyngeal swab samples were collected from both sheep species and cultured to determine if any strains of pasteurella spp. were shared on range conditions after contact of the two species. pasteurella spp. were isolated from all 38 bighorn sheep and 16 of 17 domestic sheep included in this study. the isolates were characterized on the bases of species, biotype, serot ...19979249701
atom bomb test leave infamous legacy. 19827123232
adaptability of pregnant merino ewes to the cold desert climate in nevada.grazing ability is difficult to record in animals under free-ranging conditions without sophisticated methods. alternatively, grazing ability may be indirectly inferred from changes in bw and production characteristics during the grazing period. the present study investigated the effect of grazing on resource-limited rangelands on bw, wool characteristics, and offspring weaning weights in nine hundred five 5/8, 7/8, and fullblood merino ewes of 2 to 7 yr of age during a grazing period of approxi ...201019933439
haemophilus somnus (histophilus somni) in bighorn sheep.respiratory disease and poor lamb recruitment have been identified as limiting factors for bighorn-sheep populations. haemophilus somnus (recently reclassified as histophilus somni) is associated with respiratory disease in american bison, domestic sheep, and cattle. it is also harbored in their reproductive tracts and has been associated with reproductive failure in domestic sheep and cattle. therefore, reproductive tract and lung samples from bighorn sheep were evaluated for the presence of th ...200616548330
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