Intraguild interactions and abiotic conditions mediate occupancy of mammalian carnivores: co-occurrence of coyotes-fishers-martens

The widespread eradication of large carnivores and subsequent expansion of
top mesopredators have the potential to impact species and community
interactions with ecosystem-wide implications. An example of these trophic
dynamics is the widespread establishment of coyotes following the
extirpation of wolves and mountain lions in eastern North America. Here,
we examined the occupancy of three carnivores in northern New York
considering both environmental/habitat factors and interspecific
interactions. We estimated the co-occurrence of coyotes, fishers, and
martens from a landscape-scale winter camera trap survey repeatedly
annually for three years. Martens occurred independently of both coyotes
and fishers, while fishers and coyotes displayed positive intraguild
interactions that were constant across the landscape. Both marten and
fisher first-order occupancy was driven by a combination of biotic and
abiotic factors, with both species displaying positive associations with
forest cover but antithetical responses to average snow depth. The
integral and antithetical role of snow depth in driving the occurrence of
martens (positive) and fishers (negative) in the landscape indicates that
future climatic warming could reduce the availability of current spatial
refuges for martens created by severe winter conditions. Climate-driven
alterations to established competitive interactions and co-existence
patterns between marten and fishers have critical implications for the
species' survival and conservation. We provide correlational evidence
consistent with the potential for positive top-down effects of dominant
mesocarnivores on subordinate species, with fisher occupancy increasing
conditional on the presence of coyotes across the landscape. These
findings align with the hypothesis that under certain conditions, coyotes
may facilitate certain subordinate carnivores. The evidence produced here
is consistent with hypotheses on the dynamic nature of trophic niches. We
demonstrate the need to consider the interplay between climate, habitat,
and interspecific interactions to understand wildlife occupancy patterns
and inform wildlife management in a rapidly changing world.