In northwestern Minnesota, the animal is near extinction.
Scientists say the animals are dying of "tipover disease," meaning they just weaken and fall to the ground where they are finished off by wolves and other predators.
A team of researchers from the Minnesota Department of Natural Resources and the Fond du Lac Band of Lake Superior Chippewa are trying to figure out why.
The cause might be parasites the moose have picked up from a skyrocketing deer population, or it might be a complication from warming winters.
The average midwinter temperatures in northwestern Minnesota increased about 11 degrees from 1961 to 2001, a huge change.
A wildlife biologist from the Fond du Lac band says a warming climate is a threat to the moose, but it doesn't explain everything.
