Sam Cook, Forum Communications Co., Published February 23 2012
Minnesota moose numbers down 14%
The state’s lead moose research biologist believes it’s just a matter of time before one of the state’s most iconic species disappears from the landscape.
“I would love to be wrong,” said Mark Lenarz, leader of the Forest Wildlife and Populations Research Group for the Department of Natural Resources in Grand Rapids. “But the more information we gather, the more analyses we do, it all indicates the population will continue to decline.”
The DNR announced results of its most recent aerial survey of moose on Thursday. The survey indicates the moose population dropped from about 4,900 animals in 2011 to about 4,230 this year. The population was estimated at about 8,000 in 2005.
“We’re down about half that in seven or eight years,” Lenarz said. “It’s very disturbing.”
This year’s survey showed a slight increase in the number of calves and a higher ratio of bulls to cows.
“It’s hard to get real optimistic about things,” said Mike Schrage, wildlife biologist for the Fond du Lac Band of Lake Superior Chippewa, which participates in the annual survey. “I haven’t thrown in the towel yet. It’s encouraging to see a few more calves, but there’s not a lot of reason for serious optimism.”
DNR officials say they will decide within a couple of weeks whether to offer another moose hunting season this fall, Lenarz said. Last fall, the DNR continued a bulls-only hunting season and cut the number of moose-hunting permits by more than half, from 213 in 2010 to 105 last year.
Both Schrage and Lenarz say that, biologically, there is no reason not to hold a bulls-only hunt.
“If we stop hunting tomorrow, we’re not going to see a change in the population decline,” Lenarz said. “We’re only taking bulls, and we’re not seeing a decrease in the pregnancy rate.”
Several moose studies are under way to determine why Minnesota’s moose have high mortality rates, from 18 to 20 percent.
Biologists do not have a good understanding of exactly what moose are dying from.
Of 150 adult moose radio-collared since 2002 in Minnesota, 119 have subsequently died, most from unknown causes thought to be diseases or parasites. Eleven deaths were clearly the result of wolf predation, according to the DNR. Ten moose died as a result of highway vehicle accidents. Two were killed by trains.
Biologists believe that a warming climate may be affecting moose mortality rates, and, if so, the outlook for the species is not good.
“Assuming there’s a link between climate change and high mortality rates, we have been going through a warmer than normal period,” Lenarz said. “It’s possible we may end up going through a cooler dip for a while, which will likely delay the disappearance of moose. If (mortality) is tied to climate change, the temperatures are going to be increasing over the long term. It’s a matter of whether it’s 20, 30 or 40 years, but the population is not going to come back and be stable.
“To me, climate change is a fact. Ninety-three to 96 percent of all climatologists say it’s a fact. They may not agree on the cause, but the majority say it’s linked to emissions. Even if we reduce emissions, the climate is going to continue to get warmer.”
Warm weather itself doesn’t kill moose, Lenarz said. But research on cattle, large animals who are ruminants like moose, shows they tend to stop feeding when temperatures reach 57 degrees in the summer or 23 in winter. That means they store fewer fat reserves, and dairy cattle produce less milk, Lenarz said.
The temperature stress can lead to impaired immune systems, which makes the animals more vulnerable to disease and parasites, he said.
The decline of Northeastern Minnesota moose parallels what happened to moose in northwestern Minnesota over the past three decades. There, moose numbered more than 4,000 in 1981 and crashed to only about 100 animals by 2001.
The continued decline of Northeastern Minnesota’s moose falls in line with predictions made last August by several natural resource experts who were part of the 2009 Moose Advisory Committee.
“If the decline over the past six years continues at the same rate, there could be few moose in Northeastern Minnesota by 2020,” the researchers noted in a report to the DNR.
Sam Cook writes for the Duluth News Tribune.