Moose are picky about what they eat

Updated: October 2, 2019

A bull moose feeds on aquatic vegetation Shutterstock

There’s no doubt that moose cut an intimidating figure. As the largest species in the deer family, adult males can weigh up to 1,300 pounds. It takes a lot of fuel to keep these herbivores running, and so moose consume around forty pounds of vegetation daily. But just like some people prefer carrots over broccoli, moose are discerning in their tastes.

Research from the School of Forest Resources and Environmental Science at Michigan Technological University, the United States Geological Survey, and the University of Wyoming indicates that moose are picky in their food choices, and that environmental factors like predation and weather play a role in determining what plants a moose deems worthy to eat for dinner. Understanding how moose forage for food in different conditions helps scientists understand the types of habitat moose need to survive and produce strong calves.

The study’s researchers went to the source to find out what moose were eating. Over a decade’s worth of moose droppings had been collected from Isle Royale National Park in Michigan, United States. The park consists of Isle Royale, the largest island in Lake Superior, and over two hundred surrounding smaller islands. When the collected samples were processed and placed under a polarized light microscope, the researchers were able to identify the plant species in the droppings. They applied these findings to a mathematical model to assess how moose diet choices were influenced by their environment. 

The researchers observed that moose prefer to eat rare plants in their habitat range. Moose would turn up their nose to plants that were common, while searching out and chowing down on the same plants if they were rare. But external factors like the risk of predation from grey wolves and inclement weather caused moose to become less picky in their diet choices, indicating that the search for rare plants wasn’t worth it when times were tough.

For Dr. Vince Crichton, certified wildlife biologist and retired manager of Game, Fur and Problem Wildlife with Manitoba Conservation, the best way to figure out what moose are eating is to get out into the bush and directly observe the animals. He says moose are browsers, and will feed upon a variety of tree species including trembling aspen, black poplar, and willows. Red osier dogwood, says Dr. Crichton, is “ the ice cream of the moose world.”

Moose turn to different food sources depending on the season. Dr. Crichton says that in the month of June, moose will feed on aquatic vegetation to replenish sodium and other minerals they’ve lost over the course of the winter. He was once able to capture a bull moose on video, feeding on tiny, floating duckweed plants. He observed the bull “going along in the water, having his mouth open like a big scoop, scooping this stuff up. It was amazing to see this.”

Winter is a different story. During a normal winter, moose will continue browsing on dogwoods, poplars and willows. But late in the season if the weather gets severe, moose will start stripping bark off trees. They’ll strip bark not only from standing trees, but from “trees that have been down on the ground for two or three years,” says Dr. Crichton. “There’s no nutritional value in it. It’s basically filler.”

In parts of the northeastern United States, moose have even shown a taste for fruits and vegetables. “They go after really interesting things — watermelon, brussels sprouts, and some agricultural products that drives some of the farmers bonkers,” says Dr. Crichton. 

Dr. Crichton continues to follow moose in the field to better understand their behaviour. “You’ve got to get out in the wild and see what they’re doing out there,” says Dr. Crichton. “That’s why I still get out and spend a lot of time watching what they’re doing out there throughout the year, and what they’re feeding on.”

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