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Endangered Grizzlies Feast on Local Yellowstone Moths

Nov 17, 2014 11:01 AM EST

More and more endangered grizzly bears are frequenting the southeastern part of the Greater Yellowstone ecosystem every summer, according to a recent study, in search of army cutworm moths. Given that other food resources like trout and pine nuts are in decline, the findings may have important implications for grizzlies' survival.

"We've seen an increase in the use of these moth sites in the last three years," Frank van Manen, of the Interagency Grizzly Bear Study Team in Bozeman, said according to the Billings Gazette. "Certainly it's a very intriguing food resource that we want to keep track of."

Aerial sites of 29 moth surveys inside the 9,210 square-mile area showed that the small bugs, rich with fat and protein, are especially mouth-watering to these hungry bears.

Researchers spotted 470 grizzly bears roaming the 29 moth sites, with 220 individuals at the sites this year alone, including 19 females and their cubs. Grizzly bear researchers didn't officially recognize the sites until the 1980s. Since then, they have looked more closely for moth areas within Yellowstone, so far confirming 37 sites in the ecosystem with another 16 possible locations.

"Almost 80 percent of the sites are being used," van Manen said. "But this is not a resource being used by every bear in the ecosystem."

The bears, which are included as an endangered species in the Greater Yellowstone ecosystem, can eat almost anything, from dandelions to ants. And they have plenty to choose from, considering Yellowstone National Park is home to 266 different types of plants and animals.

Some conservationists worry that because once-plentiful natural sources of protein - like cutthroat trout and whitebark pine nuts - have declined grizzly bears are in trouble.

However, given their varied diets, others insist that they are doing just fine and should be removed from the US Fish and Wildlife Service list of endangered animals. Many bear biologists believe grizzlies are adaptive enough to look for different food sources.

The decision is pending, but meanwhile the bears are happily feasting on army cutworm moths, consuming up to 40,000 a day - equal to 20,000 calories - according to another study from the Glacier National Park.

Grizzly bears (Ursus arctos horribilis) in North American used to number around 50,000, notes Defenders of Wildlife, but sadly there are only an estimated 1,800 in the lower 48 states today.

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