Researchers are working hard to find answers to why the Minnesota moose population has been dwindling. There may not be agreement on how to manage for moose—but all agree that we want to continue to see moose in northeastern Minnesota, like this magnificent bull moose spotted near the end of the Arrowhead Trail in Hovland.
This is the last story in a three-part series that takes a look at what is causing the decline in numbers of moose in Minnesota. In the last 10 years moose have been dying at an alarming rate throughout the state, and they have all but disappeared in northwestern Minnesota. Scientists and Minnesota DNR wildlife biologists are compiling information that looks at warming temperatures, diet, disease, and predators, and in time the why, or multiple whys, should be known. But whether or not the moose can be saved is another matter.
One of the problems moose face is predators. Mike Schrage, wildlife biologist with the Fond du Lac Band of Lake Superior Chippewa, has been studying this issue.
“Our generally increasing deer numbers and healthy predator populations aren’t helping,” Schrage said.
“There is still a lot of what looks like good moose habitat out there with fewer and fewer moose in it. The research on moose in northwest Minnesota showed no serious impacts from predators, but found a lot of health-related mortality and a 30-year increase in temperatures. Aggressive habitat management and closing hunting still has not recovered moose numbers in Northwestern Minnesota,” said Schrage.
Seth Moore, a wildlife biologist for the Grand Portage Band of Lake Superior Chippewa, takes a slightly different look at the wolf/bear/moose interaction.
“I have noticed that biologists these days are reluctant to indicate predation as a major cause of moose mortality. I am unsure why this is the case, but it stands to reason that when wolf populations are high, the encounter rate with moose is high too. Even if wolves eat 90 percent deer, with higher wolf numbers, more moose will get eaten. This means more calves in particular, but also more adults.
Moore noted that although he did not have data on hand regarding bear numbers, it does seem that bear population could also be a factor.
“When bear numbers are high, more calf predation by bears will occur. In my opinion, predator numbers are high due to zero harvest on wolves and the high deer numbers (that drive wolf populations). I think as a group, we biologists need to take a hard look at predation, bioenergetics of predators, and good diet studies to nail down the true proportion of mortality on moose due to predation.”
Tom Rausch, Tower Area Wildlife Manager with the Minnesota Department of Natural Resources, also thinks predation could be a major cause for the low calf-to-cow ratio of 24 calves to 100 cows. Most cows bear calves in the spring, but fewer and fewer of the calves are surviving past their first year. In 2010 the number was 28 calves to 100 cows, and Rausch said it is his gut feeling that predators are taking the calves.
If that is the case, only increasing the deer hunt, making fewer available for wolves, or taking wolves off of the endangered list and opening hunting/trapping on them will help the moose.
Global warming and habitat
The MN DNR has been carefully monitoring the decline of moose in northeastern Minnesota—down from 7,800 in 2009 to 4,900 in 2011—and after last fall’s successful hunt where 109 bull moose were taken, has pared back 2010 hunting licenses from 213 to 105 for next fall.
For the next two years DNR researchers will track 63 moose who were outfitted with GPS satellite collars. Every 20 minutes the collars will give the moose’s location; ambient temperatures will be collected every minute and neck movements in three dimensions will be recorded every minute for two years. At two years, collars will drop off and the researchers can retrieve them and collect the stored data.
When asked if this study will provide information on the effects of global warming on moose, Andy Edwards, director of the Research Management Division for the 1854 Treaty Authority, responded, “I’m not sure I would phrase it that way. I think the data we’ll be collecting is more in terms of examining how moose might be responding to the effects of global warming in whatever form it manifests itself upon moose range.
“We’re really looking at where, when, and how moose are utilizing their surrounding habitats every 20 minutes. So, yes, we’ll hopefully be able to say something about how moose are behaving on a 50-degree day in February or a 95-degree day in July. But we’re going to be limited to examining these correlations to conditions the area experiences over the next two years.
“All the variability that can occur in a two-year period would make it really tough to say global warming is forcing moose to use a certain habitat, simply because we weren’t collecting this type of information in the past. In my opinion, the real key with global warming is on the predictive side—if researchers can come to agreement on the timing, extent and impact of global warming on the landscape that currently encompasses moose range in Minnesota—then there is great potential to use the information we collect under similar conditions over the next two years to drive habitat management in a fashion that will benefit moose down the road.
“Until those predictions can be made with a high degree of certainty, I think what we’re striving to do is simply to take this close look at where, when, and how moose are using their habitat now in areas of relatively high density so we can proactively maintain that habitat where it exists, and provide it in areas where it is currently lacking.
“That may well be the best we can do. Emulating good, productive moose habitat under our current environment may not be the solution if we see a dramatic shift 50 years down the road but it certainly can’t hurt.”
Data collection continues
The various entities hoping to solve the dwindling moose population mystery will continue to work together, studying results like those obtained by the Grand Portage Band of Lake Superior in 2010. Grand Portage collared nine moose. Of those, two died. One, said Moore, was seen swimming in circles in Lake Superior and underwent euthanasia due to the fact that it was near drowning and was clearly unable to survive. Upon diagnosis by the Veterinary Diagnostic Laboratory of the University of Minnesota, it was determined to have been completely blind from a parasite in its eyes. The other known mortality occurred during a warm spell this winter. Its cause of death is unknown.”
Researchers will continue to share data such as the recent aerial survey released by the MN DNR which revealed that the number of cows to calves has fallen to a ratio of 24 calves to 100 cows, following a 14-year decline. And the proportion to twin calves to cows was at the lowest level since 1999.
Dr. Mark Lenarz, DNR wildlife biologist, said these results, coupled with what scientists have been finding through research of radio collared moose, “indicate that the population has been declining in recent years.”
The DNR has conducted aerial surveys since 1960 in northeastern Minnesota. These surveys are based on flying transects in 40 randomly selected plots spread across the Arrowhead region.
Since 2002 to 2008 a study of 150 radio-collared moose in northeastern Minnesota has shown non-hunting mortality of moose was much higher than in moose populations outside of Minnesota. Of those moose, 114 have died, most from unknown causes thought to be from disease or parasites. Ten were killed because of traffic accidents and two by trains while nine died from attacks by wolves.
The future?
When asked if any of the data will be used to shape future hunting laws, 1854 Authority’s Edwards responded, “I guess I don’t foresee any direct impact of this particular research on hunting regulations. With the research being undertaken now, we’re hoping to find ways to manage or protect habitat that might change some of those survival or reproduction rates. If successful, this may indirectly impact hunting regulations or opportunities in the future.”
The DNR will soon release its moose management and research plan and in it there will be a recommendation using bull-cow ratios as a measure to determine whether a bulls-only hunt should continue. DNR biologists will now base harvest levels on 5 percent of the estimated bull population rather than 2 percent of the estimated total moose population.
According to Lou Cornicelli, DNR big game coordinator, “This low level of harvest should allow for an increase in the proportion of bulls in the population.”
Any further decline in the bull-to-cow ratio (which is now estimated at 66 bulls to 100 cows) may result in the hunting season being cancelled all together.
All agree more research must be done before it is known how studies will be used to help forest service practices. Edwards said, “Hopefully we’ll be able to identify some practices that tribal, county, state, federal and private land managers can implement to benefit moose. It will take actions on behalf of all of those people to make a difference because management for moose is only one consideration that is taken into account.
“There are also economics and other considerations that factor in. For example, if we were to decide that the best thing to do was constantly regenerate aspen for moose, that potential action would likely be limited to a large extent by maintaining a viable timber market for aspen and the public’s desire to see more than just a young aspen forest.”
There may be more questions than answers at this time regarding how and why the moose population is declining. However, there is overwhelming consensus that the moose—Minnesota’s largest herbivore—is important to Minnesotans. It is hoped that research will lead to a better future for our magnificent moose.
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