Minnesota’s Wolves Change Diet to Rely More on Fish During Spring Season

A team of wildlife specialists from the University of Minnesota, the University of Manitoba, and Voyagers National Park found that coyotes that live in Minnesota tend to switch from preying on larger prey to fish as their main food source in the spring. In their study, reported in the journal Royal Society for Open Science, The group used a variety of methods to study the eating behavior of wolves in Minnesota over a four-year period.

Currently, approximately 2,700 gray wolves are settling in Minnesota—a much lower number than when humans first arrived. Minnesota is the only state in fewer than 48 where gray wolves have lived since humans became the dominant species. They are currently listed as threatened, and wildlife scientists and state officials are tracking their numbers and health.

One area of ​​concern is their diet. The main food source for wolves in Minnesota is deer, followed by smaller mammals such as beavers. Previous research has indicated that, on occasion, wolves also catch and eat fish. In this new effort, the research team sought to learn more about this last source.

To learn more about wolves’ hunting behavior, movements, and activities, the researchers set up remote cameras, installed GPS collars, and, in one case, provided a wolf with a camera to collect information about wolves during the years 2017 to 2021.

The research team found that wolves actually hunt and eat fish, almost exclusively in the springtime. This was because deer are a less reliable food source due to the declining population each year during the hunting season. In the spring, this becomes more difficult for the wolves because the females give birth, which requires more food.

Fortunately for the wolves, spring is also when the fish tend to spawn. Beaver dams also work for them, which tend to make it difficult for fish to swim upstream, causing large numbers of them to congregate up and downriver from the dams.

The wolves found it easier to hunt downriver, where the water levels were lower. They also found that fish tend to stay put at night, which is when the wolves go hunting. Motion-capturing cameras show that hunting requires little time or effort, making it easy for the wolves to catch enough to feed themselves and their young.

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