After the great “moose lifts” in the 1980s, researchers were confident Michigan’s moose population would continue to grow, with a projection that the population could reach numbers in the thousands within 15 years.
“It's our responsibility as resource managers to focus on seeing the health of wildlife populations that the people of Michigan care about,” Tyler Petroelje said. Petroelje is one of the main researchers studying Michigan's stagnant moose population at the state’s Department of Natural Resources.
The 1980s moose reintroduction project consisted of airlifting 59 moose by helicopter to the western Upper Peninsula. The goal was to create a self-sustaining moose population, revitalizing the native species after its decline due to habitat loss and unregulated hunting.
Since 2010, the DNR has seen the moose population growth stagnate, with population estimates between 400 and 500. That’s less than half of what was expected after the reintroduction.
This prompted a collaboration between researchers from the DNR, the Keweenaw Bay Indian Community and Northern Michigan University to look into the cause of the lack of population growth.
Many factors can impact moose survival, Petroelje said. These include vehicle collisions, predation, parasites, disease, and malnutrition.
“The population change can often be complex and driven by multiple factors,” he said.
Last February, the research group captured and sedated 20 moose: five calves, five bulls (males) and 10 cows (females) to attach GPS tracking collars and release them back into the wild. The study has been looking into moose pregnancy rates and calf survival.
Petroelje said seven cows had confirmed births, with four singletons and three sets of twins.
Now, the researchers are using non-invasive tracking methods, such as thermal sensing drones, to continue monitoring the calves.
So far, two of the calves born have died, one due to a wolf attack, and the other from “unknown trauma.”
A recent Facebook update from the DNR said the drones have found moose fur loss due to the Dermacentor albipictus parasite, known as the winter tick. Petroelje said trends of warmer winters and reduced snowfall could be leading to more ticks.
Winter ticks are not regular ticks. They stay attached to their host their entire lives. A study by Cornell University found that some moose have had over 100,000 of these ticks at a time.
“Though they do their best to detach the ticks, once attached, they are hard to shake off,” the DNR said in the update. “Winter ticks don’t carry disease, but the blood loss, irritation, and coat loss can be fatal as moose depend on thick coats to survive cold winters.”
The DNR said calves are especially at risk since they are more sensitive to cold temperatures.
Petroelje said it’s still too early to know what role, if any, winter ticks might be playing in the stagnation of Michigan’s moose population.
“Given the case that we're just in our first year and early on, we're really not trying to draw any conclusions until the data has come in,” Petroelje said.
Erin Johnston, one of the lead researchers on the study from the Keweenaw Bay Indian Community, said she is very hopeful the study will lead to some answers.
“My guess is it will be a combination of several things, but I'm really hopeful that we will have some pretty interesting outcomes from this study,” she said.
She emphasized the cultural importance of preserving the moose population for the Anishinaabe community in Michigan.
“It's important to KBIC that we encourage native wildlife and native plants on the landscape. They have a right to be here, and so we want to do whatever we can to make sure that they have what they need to hopefully flourish,” she said.
The next step for the researchers is to expand the study. They say they hope to have 50 to 60 collared moose within the next five years.
“I think that moose are a great example of a species that a lot of people are passionate about,” Petroelje said. “They have a big impact on their environment, and they're certainly an important native species to Michigan that we would like to see persist here.”
