What do caribou eat? A review of the literature on caribou diet

Webber, Quinn M. R.; Ferraro, Kristy M.; Hendrix, Jack G.; Wal, Eric Vander

doi:10.1139/cjz-2021-0162

Cited by 29 publications

(26 citation statements)

References 82 publications

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“…In arctic and subarctic regions, the potential for exploitative competition among herbivores should thus be higher during winter, when resource availability is limited (Thing 1977). We found that spatial overlap between both species was low during winter, when lichen is the predominant food item in caribou's diet (Webber et al 2022). Caribou wintering grounds in the taiga are mostly south of the area where muskoxen occur.…”

Section: Discussionmentioning

confidence: 97%

Investigating potential for competition between migratory caribou and introduced muskoxen

et al. 2023

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Several caribou (Rangifer tarandus) populations co‐occur with endemic or introduced populations of muskoxen (Ovibos moschatus), which has led to concerns about the potential competition between the species, especially in regions where the growth of muskoxen populations coincides with caribou declines. We evaluated the potential for competition between migratory caribou and an introduced muskoxen population in northern Québec, Canada, at multiple spatial scales, from 2017 to 2019. We investigated space use and habitat selection patterns of satellite‐collared caribou and muskoxen, and analyzed fecal samples using DNA metabarcoding to assess diet overlap. Annual overlap between ranges was low and occurred primarily during caribou spring migrations on the coast of Hudson Bay, and during summer on the coast of Ungava Bay. During spring, muskoxen selected shrub‐dominated areas close to the coast, whereas caribou selected rock‐substrate tundra and low elevations within their overlapping ranges. Thus, co‐occurrence was low and remained limited to the vicinity of the Hudson Bay. In summer, muskoxen selected productive coastal areas and caribou selected erect‐shrub tundra; both species selected prostrate‐shrub tundra. This led to a higher co‐occurrence in the Ungava Bay study area relative to the Hudson Bay study area. We found similarities in the diets of the 2 species at the plant family level, with shrubs being commonly consumed by both species across seasons. We conclude that, at a broad spatial scale, there was limited potential for seasonal space use and diet overlap between caribou and muskoxen in our study area. Still, multiple sources of uncertainty remain such as local impacts of herbivory by muskoxen, demographic and distribution patterns of both species, trophic interactions with predators, shared diseases and parasites, and climate change. These sources of uncertainty could be mitigated through the elaboration of local management plans and community‐based monitoring.

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Section: Discussionmentioning

confidence: 97%

Investigating potential for competition between migratory caribou and introduced muskoxen

et al. 2023

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“…Foraging apart from conspecifics reduce the costs of competition at cratering sites, which may be limited on the landscape or relatively small. We propose that while caribou generally have larger group sizes in winter (Webber &Vander Wal, 2021), groups vary in size based on movement and habitat selection behaviour presumably to balance the trade-off between competition and information acquisition. Furthermore, female caribou often have antlers, which unlike males, persist into winter.…”

Section: Discussionmentioning

confidence: 99%

“…Caribou live in fission-fusion societies (Lesmerises, Johnson, & St-Laurent, 2018), and throughout much of their range, caribou forage primarily on lichen, grasses, sedges, and other deciduous browse with access to these resources changing between the seasons (Bergerud, 1974). During winter (January to March), the landscape is covered by snow, and caribou forage primarily on lichen (Webber, Ferraro, Hendrix, & Vander Wal, 2022). Lichen is heterogeneously distributed, and access is impeded by snow and ice cover.…”

Section: Caribou As a Model Systemmentioning

confidence: 99%

Effects of the social environment on movement-integrated habitat selection

Webber

Prokopenko

Kingdon

et al. 2021

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Movement links the distribution of habitats with the social environment of animals using those habitats; yet integrating movement, habitat selection, and socioecology remains an opportunity. Here, our objective was to disentangle the roles of habitat selection and social association as drivers of collective movement in a gregarious ungulate. To accomplish this objective, we (1) assessed whether socially familiar individuals form discrete social communities and whether social communities have high spatial, but not necessarily temporal, overlap and (2) modelled the relationship between collective movement and selection of foraging habitats using socially informed integrated step selection analysis. Based on assignment of individuals to social communities and home range overlap analyses, individuals assorted into discrete social communities and these communities had high spatial overlap. By unifying social network analysis with movement ecology, we identified state-dependent social association, where individuals were less cohesive when foraging, but were cohesive when moving collectively between foraging patches. Our study demonstrates that social behaviour and space use are inter-related based on spatial overlap of social communities and state-dependent habitat selection. Movement, habitat selection, and social behaviour are linked in theory. Here, we put these concepts into practice to demonstrate that movement is the glue connecting individual habitat selection to the social environment.

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“…Caribou diet changes seasonally based on the accessibility of resources. During summer, caribou are generalists, foraging on shrubs, lichens, sedges, and herbaceous plants (Bergerud & Nolan, 1970; Webber et al, 2022). During winter, they either dig holes in the snow termed craters and consume terrestrial lichens, or forage on arboreal lichens when access to terrestrial lichens is hindered by the snow depth or its hardness (Johnson, Parker, & Heard, 2001).…”

Section: Methodsmentioning

confidence: 99%

Environmental, social, and morphological drivers of fission-fusion dynamics in a social ungulate

Goff

Hendrix

Webber

et al. 2022

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Social groups exist because individuals within the group accrue a net benefit from sharing space. The profitability of sociality, however, varies with ecological context. As ecological context varies, tension emerges among the costs and benefits of social grouping. Fission-fusion societies are fluid in their group dynamics across spatial and temporal contexts, permitting insights into how context affects whether animals choose to join or depart a group. We tested four non-mutually exclusive hypotheses driving variation in fission and fusion in caribou: the risky places, environment heterogeneity, activity budget, and social familiarity hypotheses. The risky places hypothesis predicts animals are unlikely to diffuse when habitats are open and risk of predation is elevated. The habitat heterogeneity hypothesis predicts that fission is more likely in a heterogeneous landscape due to the rising conflicts of interest between group members. The activity budget hypothesis predicts dyads associate by body size due to similar food passage rates. The social cohesion hypothesis predicts that familiar individuals are less likely to fission. We tested the hypotheses using time-to-event (time before fission) analyses and a linear model that assesses spatial, social, and body size relationships among female caribou (n = 22) on Fogo Island, Newfoundland, Canada. Contrary to our prediction for risky places, probability of fission was not influenced by habitat openness. The hypothesis of environmental heterogeneity was partially supported, as caribou remained less cohesive in environments with a higher richness of habitats. No direct evidence emerged to support the activity budget hypothesis. However, it appears that caribou maintain the strongest social bonds among variably sized individuals and these social bonds do decrease the propensity to split. Collectively, our findings showed that social interactions may depend not only on individual identity and characteristics, but also the spatial context in which these interactions occur.

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What do caribou eat? A review of the literature on caribou diet

Cited by 29 publications

References 82 publications

Investigating potential for competition between migratory caribou and introduced muskoxen

Investigating potential for competition between migratory caribou and introduced muskoxen

Effects of the social environment on movement-integrated habitat selection

Environmental, social, and morphological drivers of fission-fusion dynamics in a social ungulate

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