Minnesota’s Moose Mystery

Ashley Jones

 

Where’s Bullwinkle? Recently the iconic mammal has all but vanished from Minnesota’s Northwood’s. More concerning, wildlife professionals don’t know why.

 

Historically, northern Minnesota has been home to Alces alces, or moose. Moose are a species of ungulate, (hooved mammal) that are known for their incredible size and charisma. During the past twenty years, the state’s two moose populations have experienced precipitous declines, and it’s not for lack of attention.

 

First to go was the state’s northwestern population, with a decline from 4,000 animals in 1985 to fewer than 100 in 2009 (MAC 2009). Following this crash, the Minnesota State Legislature directed the DNR to establish a Moose Advisory Committee (MAC). The MAC’s goal was to form a Moose Management and Research Plan for the state’s northeastern population. The plan was released in 2011.

 

Direct causes of moose mortality have been identified by the MN DNR as vehicle/train collisions, predation, and poaching. Almost 80% of mortalities are unknown, with half of them thought to be health related (poor nutritional condition, disease, and parasites) (MAC 2011).

 

Hunting mortality by humans is not a powerful driver of moose numbers at this time. Annual harvest currently represents less than 3% of the total estimated population (MAC 2011).

 

Public opinion may not be uniform, but one yell can be heard louder than the rest: WOLVES. While it may be hard for well-informed bloggers to hear, the data do not uphold marauding wolves as the main problem Minnesota’s moose face today. The most concise answer to this claim can be found in the MAC’s Recovery Plan: radio telemetry data in northeast Minnesota indicate that only 10% of adult moose mortality resulted directly from wolf predation between the years 2002-2010 (MAC 2011).

 

So that leaves us with only 13% of the population being killed by people and wolves combined, there must be more to this story…

 

While there is no easy answer for what is causing moose numbers to decline, a likely factor is warming temperatures (MAC 2011).  Heat stress may be the thread linking mortality causes identified as “unknown” by the DNR, with increasing temperatures. Members of the MAC agree: “All the known causes of moose mortality (ticks, brainworm, predation, liver flukes, predation, vehicle/train collisions) can be exacerbated by heat stress.”

 

In a recent study, “Moose responded to exposure to temperatures above critical thresholds by seeking thermal shelter in mature coniferous forest and avoiding open habitat types (Van Beest et al. 2012).”

In northwestern Minnesota, where declines were severe, the landscape is dominated by agricultural land. In contrast, the northeastern portion of the state holds wetland-rich forested habitat which may provide a cool buffer to the animals in a warming environment. These differences in habitat structure could explain why the western population was so ill-equipped to deal with warming temperatures, while eastern moose have been able to persist thus far.

 

Habitat may be a very good place to focus conservation efforts because of the potential it has to lessen the negative effects of warming. That being said, habitat is not created overnight and in the privately owned-Midwest requires consenting landowners to act as stewards.

 

So the next time you or someone you know in the Northwoods pulls up on a wolf in the crosshairs, consider planting a Tamarack instead.

 

 

 

References:

 

USA. Minnesota Department of Natural Resources. Division of Fish and Wildlife. Minnesota Moose Research and Management Plan. By MAC. N.p.: n.p., 2011. Web. 9 Sept. 2012. <http://files.dnr.state.mn.us/fish_wildlife/wildlife/moose/management/mooseplan-final.pdf>.

 

USA. Minnesota Department of Natural Resources. Division of Fish and Wildlife. Moose Management and Research Plan. By MAC. N.p.: n.p., 2009. Http://files.dnr.state.mn.us/aboutdnr/reports/legislative/moose_mgmt_research.pdf. Web. 11 Sept. 2012.

 

Van Beest, Floris M., Bram Van Moorter, and Jos M. Milner. "Temperature-mediated Habitat Use and Selection by a Heat-sensitive Northern Ungulate." Animal Behaviour 3.49 (2012): n. pag. Print.