Evidence that wolves use cooperative ambush strategies to hunt beavers

Abstract

Cooperative hunting can confer fitness benefits by increasing foraging efficiency. We documented a breeding pair of wolves in the Greater Voyageurs Ecosystem of Minnesota, USA that appeared to periodically use cooperative ambushing to hunt beavers. The breeding pair primarily chose to wait-in-ambush close to one another (< 65 m) but on different beaver feeding trails, which appears advantageous because: (1) feeding trails are where beavers are most active and vulnerable on land, (2) the probability that the pair encounters a beaver is increased, and (3) either wolf can quickly assist the other in killing a beaver. The cooperative ambush strategy these wolves used appears rare for most social Carnivora but we hypothesize this behavior is widespread in areas of wolf-beaver sympatry. This observation demonstrates that novel insights into the natural history of even well-studied predators are possible when technological advancements are combined with intensive fieldwork.

KEY WORDS:

• predation
• hunting strategy
• sit-and-wait
• ambush
• GPS-cluster
• kill site
• Castor canadensis
• Canis lupus

Highlights

We documented a breeding pair of wolves in the Greater Voyageurs Ecosystem, Minnesota, USA that appeared to use cooperative ambushing to hunt beavers. The breeding pair primarily chose to wait-in-ambush close to one another (<65 m) but on different beaver feeding trails, which appears advantageous because: (1) feeding trails are where beavers are most active and vulnerable on land, (2) the probability that the pair encounters a beaver is increased, and (3) either wolf can quickly assist the other in killing a beaver. We suspect this behavior is likely widespread throughout areas of wolf-beaver sympatry.

ACKNOWLEDGMENTS

We thank many hardworking volunteers who helped collect this data. We also thank Dr L. David Mech and Dr John Fieberg for reviewing earlier drafts of this manuscript. We thank the Minnesota Environment and Natural Resources Trust Fund, University of Minnesota, National Park Service, Van Sloun Foundation, Rainy Lake Conservancy, and Voyageurs Conservancy for supporting this work.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTAL DATA

Video 1: A video detailing a cooperative beaver hunting attempt, and how we were able to locate these cooperative beaver hunting attempts based on GPS-locations from collared wolves. Video recorded in October 2019 in the Greater Voyageurs Ecosystem, Minnesota, USA. Video can be accessed here: https://youtu.be KXn_8HDNhdk

Additional information

Funding

The work was supported by the Minnesota Environment and Natural Resources Trust Fund, National Park Service, Rainy Lake Conservancy, Voyageurs Conservancy, Van Sloun Foundation, University of Minnesota.