Social rank in female reindeer (<i>Rangifer tarandus</i>): effects of body mass, antler size and age

Holand, Øystein; Gjøstein, Hallvard; Losvar, A.; Kumpula, Jouko; Smith, Martin A.; Røed, Knut; Nieminen, Mauri; Weladji, Robert B.

doi:10.1017/s0952836904005382

Cited by 73 publications

(47 citation statements)

References 63 publications

(103 reference statements)

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“…However, there is currently no evidence that male mate choice is that important in red deer or reindeer. Even though we did not use maternal dominance directly (as on Rum), dominance is highly correlated with female age and mass in our population (Holand et al 2004), suggesting that this is not due to traits measured. The lack of support for the TWM in our case may come from the fact that the herd is artificially fed during winter.…”

Section: Discussionmentioning

confidence: 86%

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

et al. 2006

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Evolutionary models of sex ratio adjustment applied to mammals have ignored that females may gain indirect genetic benefits from their mates. The differential allocation hypothesis (DAH) predicts that females bias the sex ratio of their offspring towards (more costly) males when breeding with an attractive male. We manipulated the number of available males during rut in a polygynous ungulate species, the reindeer (Rangifer tarandus), and found that a doubling of average male mass (and thus male attractiveness) in the breeding herd increased the proportion of male offspring from approximately 40 to 60%. Paternity analysis revealed indeed that males of high phenotypic quality sired more males, consistent with the DAH. This insight has consequences for proper management of large mammal populations. Our study suggests that harvesting, by generating a high proportion of young, small and unattractive mates, affects the secondary sex ratio due to differential allocation effects in females. Sustainable management needs to consider not only the direct demographic changes due to harvest mortality and selection, but also the components related to behavioural ecology and opportunities for female choice.

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Section: Discussionmentioning

confidence: 86%

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

et al. 2006

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“…That the relative allocation of resource towards antler growth (in comparison to body growth as measured by the RAL) is higher at high density suggests a real investment into antler, leading us to argue that antlers are important for both male and female calves. Longer antler is reflected in higher social rank in this population (see Holand et al 2004), beneficial in both intrasexual and intersexual competition. The effect of early summer weather variables on RAL could partially be attributed to variation in forage quality and quantity.…”

Section: Discussionmentioning

confidence: 94%

“…Antlers presumably provide a selective advantage for female reindeer in intraspecific competition, primarily during foraging, and especially during winter (Skogland 1989), allowing them to have higher dominance status (Holand et al 2004) than antlerless males during winter and spring. Indeed, males shed their antlers after the rut in October when they use their antlers in competition for mates, whereas reproductive females shed their antlers around calving.…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism and intercorhort variation in reindeer calf antler length is associated with density and weather

et al. 2005

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We analysed intercohort variability of live weight and antler length of 5,123 reindeer calves. We further assessed the influence of climate and density on the interannual variation in antler length, and discussed sex-specific resource allocation and response to climate variability. Antler length varied significantly among years and between sexes, with interaction between year and sex. Body weight and antler length were highly positively correlated, showed similar intercohort variability, and had a strong allometrical link, suggesting that antler length could be an equally reliable measure of calf condition as live weight. We found a relative measure of antler length (i.e. antler length corrected for the allometric effect of body mass) to be positively influenced by increasing density and May-June precipitation, and also decreasing May-June temperature. We attributed the effect of early summer weather to its influence on forage availability and quality as well as the level of parasitic insect harassment. Gender difference in both the allometric exponents and the interannual variability suggest that young males and females may have different tactics for relative resource allocation towards growth of antlers as compared to body mass. Because antlers are costly to produce, they may be an honest signal of individual quality for both sexes. However, we found gender-specific allometry, as female calves more than males appear to prioritize their antler growth over body mass, especially when resources are limited. Thus, our results suggest that environmental variation may influence the extent of sexual dimorphism in antler length.

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“…The smaller group sizes would allow bulls to utilize smaller patches and exert less grazing pressure within an area. Cows, which retain their antlers over the winter, would also have a competitive advantage in maintaining and/or usurp¬ ing optimal foraging locations and feeding craters (see Holand et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

Joly

2011

Ran

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I hypothesize that the distribution of barren-ground caribou (Rangifer tarandus granti) is affected by multiple, interrelated factors. These factors include, but are not limited to, terrain and snow characteristics as well as predation pressure and habitat. To test this hypothesis, I attributed caribou locations derived from satellite telemetry over a 6 year period with terrain (elevation, slope, aspect, and ruggedness), habitat characteristics, and moose density -potentially an index of wolf predation pressure. These locations were compared to random locations, attributed using the same data layers, using logistic regression techniques to develop resource selection functions (RSFs). I found that caribou moved significantly less during mid-winter than early-or late-winter and that cows moved significantly more in April than bulls due to their earlier departure on their spring migration. Distribution was different between cows and bulls. Terrain variables were important factors but were scale-dependent. Cows avoided forested areas, highlighting the importance of tundra habitats, and selected for dwarf shrub, with relatively high lichen cover, and sedge habitat types. Bulls selected for dryas, coniferous forest and dwarf shrub habitats but against lowland sedge, upland shrub and burned tundra. Cow distribution was negatively correlated with moose density at the scale of the Seward Peninsula. My results support the hypothesis that caribou distribution during winter in northwest Alaska is affected by multiple, interrelated factors. These results may be useful for researchers to track and/or model changes in future patterns of range use over winter.

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Social rank in female reindeer (Rangifer tarandus): effects of body mass, antler size and age

Cited by 73 publications

References 63 publications

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

Male phenotypic quality influences offspring sex ratio in a polygynous ungulate

Sexual dimorphism and intercorhort variation in reindeer calf antler length is associated with density and weather

Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

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