Moose are dropping dead all over the US

Moose are dying in large numbers around the United States, but the cause remains a mystery.

The population of moose around the US has decreased in many states, according to figures cited by the nonprofit Wildlife Management Institute, including by a 70 percent drop in Minnesota in 2006 and about a 35 percent drop in New Hampshire.

Maine is the only state with a growing moose population, with around 75,000 animals and counting.

Field and Stream reported that in Minnesota researchers radio-collared 116 moose of which 85 have died over the past seven years.

"There has definitely been a change. Something has been going on and we've seen it in the hunter success rates, the amount of effort required to fill a tag and in what hunters report seeing while in the field," said Justin Gude, Wildlife Research & Technical Services Bureau Chief with Montana Fish, Wildlife and Parks, according to Nature World News.

"But the one thing that is very clear is that there is not enough information — we don't have substantial evidence of a long term decline, but we need to figure out what is going on."

There are several theories about why moose numbers have declined so drastically.

Ticks can be a serious problem for moose and occur more frequently when snow melts early and when there is less snow in general. They latch on to the mammals and drain them of blood until they die.

Brain worms, which moose can catch from deer, could also be fueling the decline, as well as tree parasites, which thrive in warm weather.

Climate change has also been posited as a cause, as shorter winters and more humidity are bad for moose's immune system.

Whatever it is, it's killing off some of the continent's most beautiful creatures.