Wolf (Canis lupus) predation and scavenging of reintroduced bison (Bison bison): a hallmark of ecological restoration to boreal food webs

While it is well documented that wolves (Canis lupus) hunt and scavenge bison (Bison bison) from some long-established populations, such ecological interactions are not well known for most small, reintroduced populations in the boreal forest. Indeed, predation or scavenging of reintroduced bison in the boreal forest is rarely reported. Yet, documenting instances of bison killed or consumed is imperative to understanding the integration of reintroduced populations into local food webs and ecosystems. Such observations also indicate that reintroduced bison may be under selective pressure from their key predator. We compiled 20 verifiable observations of wolves hunting or scavenging bison from three reintroduced populations in northwestern Canada. We report the first confirmed observations of wolves feeding on bison from the 'Nahanni' and 'Pink Mountain' populations. We also report new records of wolves hunting or scavenging bison from the 'Aishihik' population. Where sex was known, most (14 of 17) bison consumed were females and 17 of 20 were adults (either sex). Contrary to other studies, we found that 7 of 20 bison consumed by wolves were aged individuals. It took 19-50 years since bison were reintroduction before verifiable observations of wolf-bison interactions emerged for these populations, indicating that wolves were likely slow to view reintroduced bison as prey and incorporate them into their diets. These observations are of value mainly because they provide unequivocal evidence that these reintroduced bison populations are becoming integrated into local food webs and beginning to be under selective pressure by their main predator, both of which are hallmarks of ecological restoration.

Automated summary

While it is known that wolves prey on bison in certain populations, their ecological interactions with reintroduced small populations in the boreal forest are not well understood. This study provides verified observations of wolves hunting or scavenging bison from three reintroduced populations in northwestern Canada. The observations show that the reintroduced bison populations are integrating into local food webs and are under selective pressure from wolves, indicating ecological restoration.