As humans build more roads and dispose of more trash high in the mountains, scavengers are outcompeting alpine species like the Arctic fox in its own territory. A greater abundance of roadkill and litter draws red foxes and other scavengers into the mountains from lower boreal areas, creating more competition for food.
“More cabins, more tourism and increased car traffic means more litter and more roadkill. For the red fox, the crow and other scavengers, it means more tempting food,” said study co-author Lars Rød-Eriksen, a researcher at the Norwegian Institute for Nature Research.
The researchers investigated how wildlife may be affected by highways across three sites in Norway using camera traps and snow tracking.
“We found that the red fox uses the road both to find food and to move from place to place. Especially in the winter, using the roadways is easier than travelling across the snowy terrain,” said Rød-Eriksen.
“Using tracks in the snow and game cameras, we were able to document that the density of red foxes increases the closer to the road one gets. The more litter and food waste they have access to, the greater the number of red foxes that find their way to the area.”
For Arctic foxes, the opposite pattern of behavior was observed.
“A lot of trash means few Arctic foxes. We found that the Arctic fox doesn’t tend to stay close to the road. This is probably not because they aren’t attracted to the road, but because the presence of the red fox makes them keep their distance.”
The Arctic fox prefers small rodents, but will still eat trash when it is available. However, Rød-Eriksen noted that the red fox is bigger and dominates in the competition between the two species.
“There are also examples of red foxes that have killed Arctic foxes. Increased access to food enables the red fox to establish itself in the high alpine zone. The search for food is especially intense in late winter.”
Crows are usually the first to spot food, but they sometimes help foxes by guiding them to specific foraging locations. However, the crows often cause problems by finding and consuming prey before the foxes ever arrive, as noted by the study authors.
“The red fox has existed in the mountains before. But it’s an invasive species and can disrupt the natural alpine ecosystem if it establishes itself there permanently, like it seems to be doing now. The Arctic fox is already an endangered species, and it seems likely that the red fox is impacting other alpine species as well, such as ptarmigan, that are ground nesters. We call it a cascade effect when several species are affected.”
Rød-Eriksen said it will be easier to tackle the littering problem than the issue of roadkill.
“Information campaigns can inform people about the consequences of throwing out and leaving trash and food scraps behind. A lot of people probably don’t give any thought to how littering can negatively impact wildlife. Other countries have stricter legislation against littering. Maybe Norway should also consider it. Personally, I think it would be effective.”
The study is published in the Journal of Applied Ecology.