Severe environmental conditions create severe conflicts? A novel ecological pathway to extreme coyote attacks on humans

1) Identifying the circumstances and causes of carnivore attacks on humans is important for prevention of future incidents as well as employing effective wildlife management strategies. Cape Breton Highlands National Park (CBHNP) in Nova Scotia has experienced multiple attacks by coyotes (Canis latrans) on humans, including a fatal attack on an adult in 2009.

2) Here we use a combination of data on space use and diet collected from 2011–2013 to reveal that limited resources and a reliance on a large ungulate (moose, Alces americanus) as the mechanism leading to aggression by coyotes in CBHNP.

3) Resident coyotes exhibited large home range sizes (mean=77.5 km2) indicative of limited resources and spatiotemporal avoidance of human activity. Carbon (d13C) and nitrogen (d15N) isotope values of sub-sampled coyote whiskers (n=32), which provide a longitudinal record of diet over the months before collection, revealed little intra- and inter-individual variation with nearly all individuals specializing on moose, a pattern that agrees with indices of natural resource availability. Specifically, stable isotope mixing models show that moose was the most important prey for most coyotes (25/32), representing between 41% and 78% of dietary inputs. Only four coyotes exhibited use of anthropogenic resources (food), and only one of seven coyotes involved in attacks on people had been consuming human foods before the attacks.

4) Synthesis and Applications: We have described a unique ecological system in which a generalist carnivore has expanded its niche to specialize on a large prey species, with the unfortunate consequence of also expanding pathways to conflicts with people. Our results suggest extreme unprovoked predatory attacks by coyotes on people are likely to be quite rare and associated with unique ecological characteristics. Extreme management actions such as bounties are unnecessary, but managers may need to employ hazing or lethal removal earlier in the conflict process than under normal circumstances. Also, users of these areas should be made aware of the risks coyotes pose and encouraged to take precautions.