Big fires might help state's moose herd
Moose typically find a scrumptious menu of new growth to eat after large forest fires such as the Pagami Creek fire, biologists say. "Historically, large burns create a lot of moose habitat -- aspen, birch, mountain maple, dogwood, hazel," said M...
Moose typically find a scrumptious menu of new growth to eat after large forest fires such as the Pagami Creek fire, biologists say.
"Historically, large burns create a lot of moose habitat -- aspen, birch, mountain maple, dogwood, hazel," said Mike Schrage, wildlife biologist for the Fond du Lac Band of Lake Superior Chippewa. "That's what moose like for browse.
That's bound to happen in years following the Pagami Creek fire, which has burned nearly 100,000 acres, mostly in the Boundary Waters Canoe Area Wilderness.
But biologists say they'll have to wait and see how much the fire will benefit Minnesota's struggling moose herd. Minnesota's moose population, whose range is both inside and outside the BWCAW, has been declining steadily since 2005. The ratio of calves to cows is at its lowest ever, and the ratio of bulls to cows also is considered low.
"I believe the Pagami Creek fire will probably be good for moose, but it's certainly not going to recover our moose herd all by itself," Schrage said.
Jim Peek, a retired University of Minnesota and University of Idaho professor of wildlife, studied moose and other wildlife following the 14,000-acre Little Indian Sioux fire northwest of Ely in 1971.
"Moose evolved in a fire environment. They evolved to take advantage of fires," Peek said from his home in Moscow, Idaho. "What we found out was that the higher (moose) densities were not in the interior of the burn, but along the periphery. They were taking advantage of food in the burn but were using the associated cover next to it. There was definitely an increase in yearling moose in that area."
But another fire near Alaska's Tanana Flats south of Fairbanks at about the same time as the Little Indian Sioux fire didn't have the same effect, Peek said, probably because productivity of moose in that population was much lower than that in Minnesota at the time.
Minnesota's current moose population also is low in productivity, biologists say. Forest habitat is not considered one of the prime limiting factors.
"I don't think moose in Northeastern Minnesota are food-limited," said Mark Lenarz, leader of the Forest Wildlife Population and Research Group in Grand Rapids for the Minnesota Department of Natural Resources.
"I still believe the fire will create lots of good moose habitat, and that will be good for our moose herd," he said, "but our moose herd problems appear to be driven primarily by health issues and maybe calf predation. We'll know better in 15 to 20 years if this fire really helped increase moose numbers or not."
The fire may have other effects that could benefit moose, Schrage said.
"This fire is burning at a time when it'll cook a lot of winter ticks," he said. "And it may cook a lot of snails that carry brainworm."
In bad years, winter ticks become so numerous they irritate moose to the point they rub their hides away and can die from exposure and blood loss. Brainworm is a parasite that can cause moose to die. It's carried by deer, which are unaffected by the parasite, and can be passed to moose when they eat snails, an intermediate host.
Biologists also are watching the forest regenerate after other recent fires in Minnesota. The 32,000-acre Cavity Lake Fire near the Gunflint Trail in 2006 and the Ham Lake Fire in 2007 (about 38,000 acres near the Gunflint and 38,000 more in Ontario) created lots of young forest habitat. Schrage has flown over those areas while doing aerial moose census work in recent years.
"I recall lots of moose using the edge of the fire where there were patches of burned and unburned forest," Schrage said. "Moose seem to be doing well along the fire perimeter and are starting to use the interior again, based only on scattered anecdotal observations."
If the habitat that follows the Pagami Creek fire does prove attractive to moose, it will likely be young moose, more than adults, that use it, Peek said.
"As soon as the shrubs become abundant enough to provide a forage base, you'll see some of those surviving calves floating through there and eventually it will get occupied," Peek said.
The only question is whether Minnesota's moose population will produce enough calves to benefit from the fire's influence.