Population response of reintroduced bighorn sheep after observed commingling with domestic sheep

Shannon, Justin M.; Whiting, Jericho C.; Larsen, Randy T.; Olson, Daniel D.; Flinders, Jerran T.; Smith, Tom S.; Bowyer, R. Terry

doi:10.1007/s10344-014-0843-y

Cited by 13 publications

(15 citation statements)

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“…Schommer and Woolever (2008),Wehausen et al (2011), mathematical models inClifford et al (2009), Cahn et al (2011), and Carpenter et al (2014, and additional data inShannon et al (2014) andSells et al (2015).…”

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confidence: 99%

Evidence based review: positive versus negative effects of livestock grazing on wildlife. What do we really know?

Schieltz

Rubenstein

2016

Environ. Res. Lett.

154

137

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More than a quarter of earth's land surface is used for grazing domestic livestock. Livestock grazing is generally assumed to negatively affect wildlife, however, a number of studies have found positive impacts as well. We conducted an evidence-based review of the existing literature using a series of livestock-and wildlife-related search words to systematically query Google Scholar and Web of Science. A total of 807 sources were included in the final list, including 646 primary sources which reported original data. The majority of studies were conducted in North America (338) or Europe (123), with many fewer from Africa (57), Australia (54), Central/South America (43), or Asia (31). Most studies examined birds (330) and mammals (262), with fewer including reptiles (91) or amphibians (58). We extracted further information from studies that included mammals on positive, negative, and neutral effects of livestock grazing on mammals. We found that livestock change vegetation structure and cover in ways important to small mammals, while ungulates may be affected more by interference competition and changes in forage quantity and quality. Community-level total abundance of small mammals typically declines with grazing. Species richness of small mammals either declines or stays the same, as many studies found a change in species composition from ungrazed to grazed sites while the number of species remained similar. Individual species responses of small mammals vary. Voles, harvest mice, cotton rats, and shrews show consistently negative responses to grazing while deer mice, kangaroo rats, ground squirrels, and lagomorphs show positive or variable responses. In general, species adapted to open habitats are often positively affected by grazing, while species needing denser cover are negatively affected. Studies of wild ungulates are more variable in methodology and quality than those for small mammals. We found more negative (n=86) than positive (n=34) ungulate responses overall, however, most studies have been on browsers and mixed feeders, namely deer and elk, and there is little available data for other groups. Although data is limited, several of the grazing species in Africa may show a trend toward positive responses, suggesting possible facilitation. For a number of species, responses varied by season. We find a strong need for additional research on ungulates of varying diets and body sizes, especially in the developing world, and across longer time scales to examine possible tradeoffs between competition and facilitation from livestock.

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confidence: 99%

Evidence based review: positive versus negative effects of livestock grazing on wildlife. What do we really know?

Schieltz

Rubenstein

2016

Environ. Res. Lett.

154

137

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“…Management of bighorn sheep habitat remains an important issue across much of western North America (Gutierrez-Espeleta et al, 2001;Lowrey and Longshore, 2017;Bleich, 2018;Boyce and Krausman, 2018). Proximity of bighorn sheep to domestic livestock allotments on public land (Cahn et al, 2011;Carpenter et al, 2014;O'Brien et al, 2014), and proximity of those wild ungulates to areas occupied by domestic sheep (O. aries) and goats (Capra hircus) on private land (Turner et al, 2004;Shannon et al, 2014), are controversial issues in the western United States. Domestic sheep and goats can transmit diseases to bighorn sheep (McClintock and White, 2007;Wehausen et al, 2011;Besser et al, 2012), and these issues are critical for the conservation and management of bighorn sheep populations (Cahn et al, 2011;Carpenter et al, 2014;O'Brien et al, 2014).…”

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confidence: 99%

Determining Timing of Births and Habitat Selection to Identify Lambing Period Habitat for Bighorn Sheep

et al. 2020

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“…Indeed, harvest restricted to males, and a conservative harvest of few, large males has a negligible effect on demography of polygynous ungulates (McCullough , 2001; Clutton‐Brock et al ; Mysterud et al ) and, with the exception of exceedingly high harvest rates (Milner‐Gulland et al ), does almost nothing to limit population size (McCullough ). Unless exposed to heavy mortality from predation or disease (Cassirer et al , Johnson et al , Shannon et al ), male‐only harvest results in populations that are inherently regulated by their habitat and that, by consequence, are experiencing varying levels of nutritional limitation.…”

Section: The Trifecta: Age Genetics and Nutritionmentioning

confidence: 99%

“…Epizootic pneumonia outbreaks caused by bacterial respiratory pathogens are the underlying influence of massive mortality events, but frequency and intensity of die‐offs are inconsistent and infections do not always manifest in disease (Miller et al , Cassirer et al , Shannon et al ). Indeed, chronically infected animals sometimes continue to persist in affected populations (Plowright et al ).…”

Section: The Trifecta: Age Genetics and Nutritionmentioning

confidence: 99%

“…Translocation efforts have been an effective management tool for establishment and supplementation of some populations , Krausman 2000, Hurley et al 2015, and concomitantly may be a tool to reduce population abundance and, presumably, density-dependent effects within source populations. Nevertheless, translocations are expensive (Bleich 1990), politically challenging (Bleich 2005(Bleich , 2016, not always successful (Singer et al 2000), and difficult because locations offering viable habitat without livestockrelated conflicts are increasingly rare (Singer et al 2000, Shannon et al 2014. Although effective in aiding conservation efforts in reestablishment of bighorn sheep throughout their range (Hurley et al 2015), translocation is unlikely to be a long-term solution to regulating density of sheep populations (Rominger and Goldstein 2006).…”

Section: Where Do We Go From Here?mentioning

confidence: 99%

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Horn size and nutrition in mountain sheep: Can ewe handle the truth?

et al. 2017

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Horns, antlers, and other horn-like structures are products of sexual selection, confer reproductive advantages, and are heritable and honest indicators of individual quality. In addition to serving key biological functions, horns and antlers garner societal interest that, when combined with the powerful motivation to acquire trophy animals, likely has spawned a growing hornographic culture fixated on males with exceptional horn-like structures. The concern that harvest of large, fast-growing males may cause evolutionary change to the very trait being sought has been the source of controversy in the popular and scientific literature over the past 2 decades. Mountain sheep (i.e., bighorn and thinhorn; Ovis spp.), possibly the only large ungulates in North America managed almost exclusively as trophy species throughout their ranges, embody this controversy, which has led to polarizing views among scientists and stakeholders as to how mountain sheep should be managed. Our goal in this commentary was to discuss the relative contributions of the key ecological and intrinsic factors that influence horn growth, how those factors might interact with harvest strategies, and identify what determinants of horn size are most amenable to management and most effective in achieving desired outcomes. Despite repeated results demonstrating that age or nutrition frequently override genetic contributions to size of horns, attention has been given to the role of genetics and its relationship to harvest of mountain sheep. Given the hyperbole surrounding trophy management and big horns, we suggest the importance of females in the management of mountain sheep has been largely forgotten. Maternal condition can instigate life-long effects on size and growth of males (via maternal effects), and abundance of females, in turn, affects nutritional limitation within populations through density-dependent feedbacks. If production of males with large horns is an objective, we contend that management programs should, integrate monitoring of nutritional status of populations, and where evidence indicates nutritional limitation through density dependence, seek to regulate abundance and per capita nutrition via harvest of females. We propose that extrinsic regulation (i.e., removal by harvest or translocation) is the most effective way to manage per capita availability of forage resources and, thus, nutritional limitation on growth of males. Not only can female harvest improve growth in body size and horns of males through enhanced nutrition of growing males and their mothers, such management also 1) may yield a nutritional buffer against environmental stochasticity and erratic population fluctuations, 2) be employed in areas where other management alternatives such as habitat manipulation may not be feasible, 3) may reduce frequency or magnitude of epizootic die-offs, and 4) will increase hunter opportunity and involvement in management. Ultimately, we call for greater recognition of the pervasive role of the ewe, and other female ungulat...

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Population response of reintroduced bighorn sheep after observed commingling with domestic sheep

Cited by 13 publications

References 40 publications

Evidence based review: positive versus negative effects of livestock grazing on wildlife. What do we really know?

Evidence based review: positive versus negative effects of livestock grazing on wildlife. What do we really know?

Determining Timing of Births and Habitat Selection to Identify Lambing Period Habitat for Bighorn Sheep

Horn size and nutrition in mountain sheep: Can ewe handle the truth?

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