Interference competition between wolves and coyotes during variable prey abundance

Interference competition occurs when two species have similar resource
requirements and one species is dominant and can suppress or exclude the
subordinate species. Wolves (Canis lupus) and coyotes (C. latrans) are
sympatric across much of their range in North America where white-tailed
deer (Odocoileus virginianus) can be an important prey species. We
assessed the extent of niche overlap between wolves and coyotes using
activity, diet, and space use as evidence for interference competition
during 3 periods related to the availability of white-tailed deer fawns in
the Upper Great Lakes region of the USA. We assessed activity overlap (Δ)
with data from accelerometers onboard global positioning system (GPS)
collars worn by wolves (n = 11) and coyotes (n = 13). We analyzed wolf and
coyote scat to estimate dietary breadth (B) and food niche overlap (α). We
used resource utilization functions (RUFs) with canid GPS location data,
white-tailed deer RUFs, ruffed grouse (Bonasa umbellus) and snowshoe hare
(Lepus americanus) densities, and landscape covariates to compare
population-level space use. Wolves and coyotes exhibited considerable
overlap in activity (Δ = 0.86–0.92), diet (B = 3.1–4.9; α = 0.76–1.0), and
space use of active and inactive RUFs across time periods. Coyotes relied
less on deer as prey compared to wolves and consumed greater amounts of
smaller prey items. Coyotes exhibited greater population-level variation
in space use compared to wolves. Additionally, while active and inactive,
coyotes exhibited greater selection of some land covers as compared to
wolves. Our findings lend support for interference competition between
wolves and coyotes with significant overlap across resource attributes
examined. The mechanisms through which wolves and coyotes coexist appear
driven largely by how coyotes, a generalist species, exploit narrow
differences in resource availability and display greater population-level
plasticity in resource use.