Free rein: Are feral horses competing with native ungulates in British Columbia?

Abstract Feral species have been shown to contribute to wildlife declines and ecosystem degradation. Feral horses ( Equus caballus ) can be an important competitor of native ungulate species, preventing access to habitats or water resources. The Chilcotin Plateau in west‐central British Columbia, Canada, has been home to a population of feral horses for 250 years, but the impacts of this population on the ecosystem are not well understood. There is particular concern about competition between feral horses and 2 important cultural and game species in the region, moose ( Alces alces ) and mule deer ( Odocoileus hemionus ), with horses potentially competing with moose for wetlands and mule deer for water sources. We used camera traps deployed across a landscape with and without horse occurrence to evaluate evidence of competitive exclusion of moose and mule deer by feral horses at 2 scales: 1) landscape‐scale spatial avoidance and differential habitat selection between a patch with horses and the rest of the landscape, and 2) patch‐scale spatiotemporal avoidance where all species co‐occurred. While moose and feral horses both used wetlands, we did not find evidence that moose avoided horses. Neither feral horses nor mule deer showed increased use of areas close to water sources, indicating that water is not limiting in this system. Mule deer were less likely to use the patch with horses compared to similar low‐elevation patches without horses, potentially indicating landscape‐scale avoidance, but did not exhibit patch‐scale spatiotemporal avoidance where they co‐occurred with horses. We did not find strong evidence that horses are negatively affecting moose or mule deer in this region through competition. However, we recommend further research to investigate other potential impacts of feral horses, such as through grazing and subsidies to predators, to determine if management of this feral horse population is necessary.