Data for the article: Trophic niche partitioning between two prey and their incidental predators revealed various threats for an endangered species

Documenting trophic niche partitioning and resource use within a community
is critical to evaluate underlying mechanisms of coexistence, competition
or predation. Detailed knowledge about foraging is essential as it may
influence the vital rates, which, in turn, can affect trophic
relationships between species and population dynamics. The aims of this
study were to evaluate resource and trophic niche partitioning in
summer/autumn between the endangered Atlantic-Gaspésie caribou (Rangifer
tarandus caribou) population, moose (Alces americanus) and their
incidental predators, the black bear (Ursus americanus) and coyote (Canis
latrans), and to quantify the extent to which these predators consumed
caribou. Bayesian isotopic analysis showed a small overlap in trophic
niche for the two sympatric ungulates suggesting a low potential for
resource competition. Our result also revealed that caribou occupied a
larger isotopic niche area than moose, suggesting a greater diversity of
resources used by caribou. Not surprisingly, coyote consumed mainly deer
(Odocoileus virginianus), moose, snowshoe hare (Lepus americanus), and
occasionally caribou, while bears consumed mainly vegetation and, to a
lesser extent, moose and caribou. As coyotes and bears also feed on plant
species, we documented trophic niche overlap between caribou and their
predators, as searching for similar resources can force them to use the
same habitats and thus increase the encounter rate and, ultimately,
mortality risk for caribou. Although the decline of the Gaspésie caribou
population is mostly driven by habitat-mediated predation, we found
evidence that the low level of resource competition with moose added to
the shared resources with incidental predators, mainly bears, may
contribute to jeopardize the recovery of this endangered caribou
population. Highlighting the trophic interaction between species is needed
to establish efficient conservation and management strategies to insure
the persistence of endangered populations. The comparison of trophic
niches of species sharing the same habitat or resources is fundamental to
evaluate the mechanisms of coexistence or competition and eventually
predict the consequences of ecosystem changes in the community.