BISMARCK, N.D. – There was a time not so many years ago when a moose sighting outside of the Turtle Mountain or Pembina Hills areas of North Dakota was rather uncommon.

Recently, however, a young bull moose that has at least temporarily made Bismarck and Mandan home over the past couple of weeks has captured the public's attention. That's because this part of the state is not considered "traditional" moose habitat.

Mostly moose are thought of as woodland creatures, evoking images of the huge animal chest-deep in a slough feeding on aquatic vegetation.

At a time when moose populations are declining in surrounding states like Minnesota, North Dakota's moose are doing quite well — and on the prairie, of all places.

That said, parts of North Dakota are having the same problems with moose disappearing from their traditional ranges, said Bill Jensen, a big game biologist for the North Dakota Game and Fish Department.

Two of the primary hunting units for the largest members of the deer family — in the Turtle Mountains and around the Pembina Hills — are closed because of low numbers.

Jensen said it's suspected the reason for the decline is the same here as it is in northwestern Minnesota: disease. He said moose are prone to brain worms, a parasite that is carried by, but not fatal to, deer.

While moose seem to be disappearing from their normal habitat, they seem to be finding the prairie and other open areas in the northwestern part of the state suitable.

Between 1993 and 2007, the moose population in the Pembina Hills went from 260 to 11.

During roughly the same period, the Game and Fish Department increased the number of moose licenses available in the extreme northwest part of the state. Last year there were 69 moose tags issued in the unit. This year, the number is down to 50.

Jason Smith, a Game and Fish Department big game biologist in Jamestown, said the department is gearing up for a second study on moose in the state, the first being conducted from 2003-07.

"All around us, moose are in decline," Smith said.

"In North Dakota, we don't have moose where we should have moose, and we have moose where we shouldn't have moose."

Smith calls it the "prairie moose phenomenon." Smith said specific numbers of moose in the state aren't known, but population trends indicate the losses in the northern part of the state are being offset by the increases on the prairie.

In 2005-06, Jim Maskey, a professor of biology at the University of Mary in Bismarck, was a graduate student at the University of North Dakota working on a radio-collared study of moose in the Lonetree Wildlife Management Area near Harvey. He will be working on the new study as well.

Maskey said the prairie moose are probably taking advantage of several factors that explain why their numbers are growing in nontraditional areas.

One, transitions from small grain crops to row crops like corn and sunflowers have given moose alternative food sources. Still, he said moose are browsers and 70 percent of their diet comes from trees and shrubs.

Second, Maskey said, as tree and shelterbelt plantings on the prairie have matured in the past several decades, moose are using them for food and cover.

Wetland areas in the prairie also have been abundant, adding to the habitat moose are accustomed to finding in their historic range in North Dakota.

Third, he said, the brain worms, which are found in snails and slugs, aren't as common on the prairie as they are in forested areas, so the incidence of disease is lower.