Resilience in Ecosystems

A red fox and a raven scavenge a wolf-killed moose.

NPS

As an opportunistic and often omnivorous carnivore, red foxes are no strangers to persisting. Known as curious creatures, many Isle Royale visitors share gleeful stories about “camp foxes” – foxes that are frequently sighted around busy campgrounds, intrepidly observing human activities, and wondering if they may be the lucky benefactor of a forgotten granola bar, or a salty, sweaty (delicious!) sock.

When wolves were reintroduced to Isle Royale in 2018, island carnivores had no choice but to re-establish forgotten relationships. Recent research from the NPS and the Department of Forest and Wildlife Ecology at the University of Wisconsin – Madison, examined the impacts of wolf reintroduction, revealing insights into the persistence of species who must adapt to change within an isolated island ecosystem.

After reintroduction, wolves initially limited where foxes went – they naturally wanted to avoid the larger and more dominant predators. In response to these newly imparted limitations, foxes started to more frequently exploit camp areas and the food resources that are associated with humans.

Human resources and space use can have a strong role in shaping carnivore interactions. On Isle Royale, humans likely shielded foxes from wolves by providing a consequence-free alternative food resource, as opposed to scavenging wolf kills. The pervasive and persistent impact of human presence in an isolated, wilderness ecosystem can have enduring impact – when examining fox tissue, research reflected a diet made up largely of human foods.

As the Isle Royale ecosystem responds to new or forgotten dynamics, and fox resume their typical behaviors in the presence of wolves, this research imparts key lessons. The first is crucial: never feed wildlife and always properly secure your food. The second, less apparent yet equally significant, is that persistence in the face of change ensures survival.

Johnathan Pauli
Department of Forest & Wildlife Ecology
University of Wisconsin