Sexual segregation in North American elk: the role of density dependence

Stewart, Kelley M.; Walsh, Danielle R.; Kie, John G.; Dick, Brian L.; Bowyer, R. Terry

doi:10.1002/ece3.1397

Cited by 16 publications

(13 citation statements)

References 71 publications

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“…Hence, we propose that available habitat mediates the degree to which SSL sexual segregation is expressed, rather than individual-based limiting factors per se. Adult males breeding in Argentina were tracked from a substantially larger colony than the Falkland Islands (1300 pups versus 328 pups, respectively), so density dependence may also promote sexual segregation in Argentina through in creased intersexual competition, as is reported for terrestrial taxa (Campagna et al 2001, Stewart et al 2015.…”

Section: Discussionmentioning

confidence: 99%

“…Sexual segregation in habitat use is ubiquitous in vertebrates and its influence on animal distribution, behaviour and survival can be profound (Ruckstuhl & N euhaus 2000, Jiménez et al 2015). Yet, while the ecological consequences of sexual segregation in habitat use are clear, the underlying causes are difficult to differentiate because critical tests of hypotheses are difficult to obtain (Ruckstuhl & N euhaus 2000, Main 2008, Stewart et al 2015.…”

Section: Introductionmentioning

confidence: 99%

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Sexual segregation in habitat use is smaller than expected in a highly dimorphic marine predator, the southern sea lion

Baylis

Orben

Costa

et al. 2016

Mar. Ecol. Prog. Ser.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sexual segregation in habitat use is smaller than expected in a highly dimorphic marine predator, the southern sea lion

Baylis

Orben

Costa

et al. 2016

Mar. Ecol. Prog. Ser.

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“…We also estimated partial correlation coefficients between group-SSAS interpretations and TGS, controlling for population abundance; and between group-SSAS and population abundance, controlling for TGS [ 48 ]. Sexual segregation might be density-dependent [ 17 , 32 ]. Furthermore, typical group size is related to male abundance, and male abundance can be correlated to population abundance [ 49 ].…”

Section: Methodsmentioning

confidence: 99%

“…Associated with the wider forage niche of males is that males tend to show less site tenacity than females [ 30 ]. Furthermore, females, burdened with parental care, tend to select habitat that possesses fewer lethal risks [ 31 , 32 ]. Males, on the other hand, with a large body size, greater forage demands, and no burdens from parental care might use forage habitat with greater lethal risks [ 33 ].…”

Section: Introductionmentioning

confidence: 99%

Male group size, female distribution and changes in sexual segregation by Roosevelt elk

Peterson

Weckerly

2017

PLoS ONE

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Sexual segregation, or the differential use of space by males and females, is hypothesized to be a function of body size dimorphism. Sexual segregation can also manifest at small (social segregation) and large (habitat segregation) spatial scales for a variety of reasons. Furthermore, the connection between small- and large-scale sexual segregation has rarely been addressed. We studied a population of Roosevelt elk (Cervus elaphus roosevelti) across 21 years in north coastal California, USA, to assess small- and large-scale sexual segregation in winter. We hypothesized that male group size would associate with small-scale segregation and that a change in female distribution would associate with large-scale segregation. Variation in forage biomass might also be coupled to small and large-scale sexual segregation. Our findings were consistent with male group size associating with small-scale segregation and a change in female distribution associating with large-scale segregation. Females appeared to avoid large groups comprised of socially dominant males. Males appeared to occupy a habitat vacated by females because of a wider forage niche, greater tolerance to lethal risks, and, perhaps, to reduce encounters with other elk. Sexual segregation at both spatial scales was a poor predictor of forage biomass. Size dimorphism was coupled to change in sexual segregation at small and large spatial scales. Small scale segregation can seemingly manifest when all forage habitat is occupied by females and large scale segregation might happen when some forage habitat is not occupied by females.

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“…Consequently, growth rate of horns or antlers is likely to be slower at higher densities than at lower densities with respect to nutritional carrying capacity because poor maternal nutrition can result in a negative maternal effect combined with limited resources available for growth of young and adult males. Among sexually dimorphic species, females compete largely with each other and young, and males compete with other males because the sexes segregate throughout much of the year (Bleich et al , Kie and Bowyer , Bowyer , Stewart et al ). For mountain sheep, young males typically remain with female groups until 2–4 years old when they disperse to join groups of males (Geist , Festa‐Bianchet , Bleich et al ).…”

Section: The Trifecta: Age Genetics and Nutritionmentioning

confidence: 99%

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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Sexual segregation in North American elk: the role of density dependence

Cited by 16 publications

References 71 publications

Sexual segregation in habitat use is smaller than expected in a highly dimorphic marine predator, the southern sea lion

Sexual segregation in habitat use is smaller than expected in a highly dimorphic marine predator, the southern sea lion

Male group size, female distribution and changes in sexual segregation by Roosevelt elk

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

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