Survival of Adult Female Bighorn Sheep Following a Pneumonia Epizootic

Dekelaita, Daniella J.; Epps, Clinton W.; Stewart, Kelley M.; Sedinger, James S.; Powers, Jenny G.; Gonzales, Ben J.; Abella‐Vu, Regina K.; Darby, Neal W.; Hughson, Debra L.

doi:10.1002/jwmg.21914

Cited by 19 publications

(37 citation statements)

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“…We observed similar temporal patterns to those studies, with most mortality related to disease in our study occurring between 1.5 and 3-months after parturition. In the Mojave Desert of California, in a 3-year study of desert bighorn sheep following an outbreak of M. ovipneumoniae , the proportion of juveniles surviving varied from 0.00 to 0.92 in populations where at least five juveniles were monitored, and survival in most populations improved in later years ( Dekelaita et al, 2020 ). Unlike Cassirer et al (2013) and Smith et al (2014) , we did not address the effect of predators on juvenile survival.…”

Section: Discussionmentioning

confidence: 99%

“…Population-level responses to M. ovipneumoniae outbreaks, however, may vary widely. Considerable variation has been observed in levels of all-age mortality at first contact, subsequent adult survival, and juvenile survival in following years among populations and across evolutionary lineages and habitats ( Cassirer et al, 2018 ; Dekelaita et al, 2020 ). That variation has been hypothesized to stem from numerous causes, including strain virulence ( Kamath et al, 2019 ), nutritional factors such as forage quality and population density ( Dekelaita et al, 2020 ), stochastic factors such as the presence of chronic carriers ( Cassirer et al, 2018 ; Garwood et al, 2020 ), genetic diversity of host populations ( Cassirer et al, 2018 ), and phenological differences resulting in different patterns of aggregation, contact, and dispersal ( Cassirer et al, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

“…Considerable variation has been observed in levels of all-age mortality at first contact, subsequent adult survival, and juvenile survival in following years among populations and across evolutionary lineages and habitats ( Cassirer et al, 2018 ; Dekelaita et al, 2020 ). That variation has been hypothesized to stem from numerous causes, including strain virulence ( Kamath et al, 2019 ), nutritional factors such as forage quality and population density ( Dekelaita et al, 2020 ), stochastic factors such as the presence of chronic carriers ( Cassirer et al, 2018 ; Garwood et al, 2020 ), genetic diversity of host populations ( Cassirer et al, 2018 ), and phenological differences resulting in different patterns of aggregation, contact, and dispersal ( Cassirer et al, 2018 ). Indeed, bighorn sheep inhabit ecosystems ranging from the arid deserts of northern Mexico and the southwestern United States of America to the frigid northern Rocky Mountains of Alberta and exhibit significant phenotypic variation and evidence of local adaptation ( Wehausen & Ramey II, 2000 ; Wiedmann & Sargeant, 2014 ; Malaney et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

“…In the Mojave Desert of the southwestern United States of America, desert bighorn sheep occupy pockets of isolated mountain ranges surrounded by low-lying desert but linked by inter-mountain movements, resulting in natural metapopulations ( Bleich et al, 1996 ). M. ovipneumoniae in this system appears to have been present periodically ( Shirkley et al, in press ), and impacts on adult survival and juvenile recruitment appear to be highly variable ( Dekelaita et al, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

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Impact ofMycoplasma ovipneumoniaeon juvenile bighorn sheep (Ovis canadensis) survival in the northern Basin and Range ecosystem

Spaan

Epps

Crowhurst

et al. 2021

PeerJ

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Determining the demographic impacts of wildlife disease is complex because extrinsic and intrinsic drivers of survival, reproduction, body condition, and other factors that may interact with disease vary widely. Mycoplasma ovipneumoniae infection has been linked to persistent mortality in juvenile bighorn sheep (Ovis canadensis), although mortality appears to vary widely across subspecies, populations, and outbreaks. Hypotheses for that variation range from interactions with nutrition, population density, genetic variation in the pathogen, genetic variation in the host, and other factors. We investigated factors related to survival of juvenile bighorn sheep in reestablished populations in the northern Basin and Range ecosystem, managed as the formerly-recognized California subspecies (hereafter, “California lineage”). We investigated whether survival probability of 4-month juveniles would vary by (1) presence of M. ovipneumoniae-infected or exposed individuals in populations, (2) population genetic diversity, and (3) an index of forage suitability. We monitored 121 juveniles across a 3-year period in 13 populations in southeastern Oregon and northern Nevada. We observed each juvenile and GPS-collared mother semi-monthly and established 4-month capture histories for the juvenile to estimate survival. All collared adult females were PCR-tested at least once for M. ovipneumoniae infection. The presence of M. ovipneumoniae-infected juveniles was determined by observing juvenile behavior and PCR-testing dead juveniles. We used a known-fate model with different time effects to determine if the probability of survival to 4 months varied temporally or was influenced by disease or other factors. We detected dead juveniles infected with M. ovipneumoniae in only two populations. Derived juvenile survival probability at four months in populations where infected juveniles were not detected was more than 20 times higher. Detection of infected adults or adults with antibody levels suggesting prior exposure was less predictive of juvenile survival. Survival varied temporally but was not strongly influenced by population genetic diversity or nutrition, although genetic diversity within most study area populations was very low. We conclude that the presence of M. ovipneumoniae can cause extremely low juvenile survival probability in translocated bighorn populations of the California lineage, but found little influence that genetic diversity or nutrition affect juvenile survival. Yet, after the PCR+ adult female in one population died, subsequent observations found 11 of 14 ( 79%) collared adult females had surviving juveniles at 4-months, suggesting that targeted removals of infected adults should be evaluated as a management strategy.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact ofMycoplasma ovipneumoniaeon juvenile bighorn sheep (Ovis canadensis) survival in the northern Basin and Range ecosystem

Spaan

Epps

Crowhurst

et al. 2021

PeerJ

Self Cite

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“…Pneumonia has hindered bighorn conservation efforts for decades (Cassirer et al, 2018;Pils and Wilder, 2018). The polymicrobial infection leads to high initial mortality rates in the wild sheep, especially lambs, and may be carried by individuals for years (Besser et al, 2017;Plowright et al, 2017;Dekelaita et al, 2020). Wildlife managers widely recognize that any close contact between bighorn and domestic sheep puts bighorn at risk for an all-age die-off, even as domestic sheep remain healthy (Gunn et al, 2008;Cassirer et al, 2018).…”

Section: Trophy Sheep and Contested Land Uses: Preventing Spill Back Of Pneumonia In The Western Usmentioning

confidence: 99%

The Emotional Dimensions of Animal Disease Management: A Political Ecology Perspective for a Time of Heightened Biosecurity

2021

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The ongoing devastation of the Covid-19 pandemic has brought new urgency to questions surrounding the origins, management, and complex dynamics of infectious diseases. In this mini review, we use growing international concern over the pandemic potential of emerging infectious diseases as motivation for outlining a research approach to study the emotional dimensions of animal disease management. We sketch out this important analytical terrain by first locating opportunities for literature on the biosecurization of nature to intersect with the emerging field of emotional political ecology. Second, we describe three biosecurity contexts and environmental conflicts at the wildlife-livestock interface: African swine fever in wild boar, brucellosis in elk, and pneumonia in bighorn and domestic sheep. We argue that in these “contact zones,” a focus on emotions can add a new layer of explanation for analyzing the manifestations, implications, and varied experiences of biosecurity.

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Natural history of a bighorn sheep pneumonia epizootic: Source of infection, course of disease, and pathogen clearance

Besser

Cassirer

Lisk

et al. 2021

Ecology and Evolution

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A respiratory disease epizootic at the National Bison Range (NBR) in Montana in 2016–2017 caused an 85% decline in the bighorn sheep population, documented by observations of its unmarked but individually identifiable members, the subjects of an ongoing long‐term study. The index case was likely one of a small group of young bighorn sheep on a short‐term exploratory foray in early summer of 2016. Disease subsequently spread through the population, with peak mortality in September and October and continuing signs of respiratory disease and sporadic mortality of all age classes through early July 2017. Body condition scores and clinical signs suggested that the disease affected ewe groups before rams, although by the end of the epizootic, ram mortality (90% of 71) exceeded ewe mortality (79% of 84). Microbiological sampling 10 years to 3 months prior to the epizootic had documented no evidence of infection or exposure to Mycoplasma ovipneumoniae at NBR, but during the epizootic, a single genetic strain of M. ovipneumoniae was detected in affected animals. Retrospective screening of domestic sheep flocks near the NBR identified the same genetic strain in one flock, presumptively the source of the epizootic infection. Evidence of fatal lamb pneumonia was observed during the first two lambing seasons following the epizootic but was absent during the third season following the death of the last identified M. ovipneumoniae carrier ewe. Monitoring of life‐history traits prior to the epizootic provided no evidence that environmentally and/or demographically induced nutritional or other stress contributed to the epizootic. Furthermore, the epizootic occurred despite proactive management actions undertaken to reduce risk of disease and increase resilience in this population. This closely observed bighorn sheep epizootic uniquely illustrates the natural history of the disease including the (presumptive) source of spillover, course, severity, and eventual pathogen clearance.

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Survival of Adult Female Bighorn Sheep Following a Pneumonia Epizootic

Abstract: Beginning in the early 1900s, poly-factorial, poly-microbial pneumonia was identified as a disease affecting bighorn sheep (Ovis canadensis) and it continues to threaten bighorn populations, posing an ongoing management challenge. In May

Cited by 19 publications

References 77 publications

Impact ofMycoplasma ovipneumoniaeon juvenile bighorn sheep (Ovis canadensis) survival in the northern Basin and Range ecosystem

Impact ofMycoplasma ovipneumoniaeon juvenile bighorn sheep (Ovis canadensis) survival in the northern Basin and Range ecosystem

The Emotional Dimensions of Animal Disease Management: A Political Ecology Perspective for a Time of Heightened Biosecurity

Natural history of a bighorn sheep pneumonia epizootic: Source of infection, course of disease, and pathogen clearance

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