If two individuals can mate and produce fertile offspring does that make them the same species

I work for the Fish and Wildlife Service on endangered species issues, and one of the more common is hybridization of endangered or threatened species with other species. Such hybridization generally occurs because the RIMs that have evolved between two species are broken down due to human actions. For instance wolves may occasionally interbreed with coyotes if their pack structure and prey base are disrupted, or northern spotted owls may breed with barred owls that come into the area due to loss of old-growth forests.