Examining spatial patterns of selection and use for an altered predator guild

Anthropogenic disturbances have altered species’
distributions potentially impacting interspecific interactions.
Interference competition is when one species denies
a competing species access to a resource. One mechanism of
interference competition is aggression, which can result in
altered space-use of a subordinate species due to the threat
of harm, otherwise known as a ‘landscape of fear’. Alternatively,
subordinates might outcompete dominant species in
resource-poor environments via a superior ability to extract
resources. Our goal was to evaluate spatial predictions of
the ‘landscape of fear’ hypothesis for a carnivore guild in Newfoundland, Canada, where coyotes recently immigrated.
Native Newfoundland carnivores include red foxes, Canada
lynx, and black bears. We predicted foxes and lynx would
avoid coyotes because of their larger size and similar dietary
niches. We used scat-detecting dogs and genetic techniques
to locate and identify predator scats. We then built resource
selection functions and tested for avoidance by incorporating
predicted values of selection for the alternative species into
the best supported models of each species. We found multiple
negative relationships, but notably did not find avoidance
by foxes of areas selected by coyotes. While we did
find that lynx avoided coyotes, we also found a reciprocal
relationship. The observed patterns suggest spatial partitioning
and not coyote avoidance, although avoidance could
still be occurring at different spatial or temporal scales.
Furthermore, Newfoundland’s harsh climate and poor soils
may swing the pendulum of interspecific interactions from
interference competition to exploitative competition, where
subordinates outcompete dominant competitors through a
superior ability to extract resources.