Northern Wilds

Research Biologist Mark Keech (left) and MN Zoo Veterinarian Tiffany Wolf (right) work with 800­-pound cow moose #294, fitting her with a radio collar and taking samples that will help researchers study the cause of increased mortality in the Northeastern Minnesota moose population.  — Photo By Brian Peterson,  Minneapolis Star-Tribune

Mike Schrage has walked up to northeastern Minnesota moose that should have been in the prime of their lives. Instead, they’re dead on the ground and, by all appearances, they just tipped over.

“You come up on these carcasses and it looks like they just laid down and died,” said Schrage, wildlife biologist with the Fond du Lac Band of Lake Superior Chippewa.

Some of the moose are emaciated, while some of the bulls have poor antler development. Researchers haven’t put their finger on the cause, yet, but are working to narrow the possibilities as part of an ongoing study. And they’re hoping to do it so the herd in the northeast doesn’t turn out like the population in the northwest, which has dropped precipitously in recent years and now numbers fewer than 100 animals.

“To me, it indicates there is a parasite or disease issue out there,” Schrage said. “The other possibility is the disease/parasite issues are also linked to the climate – if climate change is creating conditions that are more favorable for the spread of disease or increased populations of parasites.”

Last week, researchers from the Fond du Lac Band, the 1854 Treaty Authority, the Minnesota DNR, and the Minnesota Zoo were back in the northeast, continuing a moose study that began in 2002. They radio-collared cow moose and took a variety of samples in hopes of better understanding why the herd in that part of the state has been on a steady decline of late. The plan was to put collars on 35 cows (it ended up being 34); 28 animals collared previously are still on the air, including some collared when the study began in 2002.

The other moose have died – some killed by hunters, some by wolves, some by cars. But the majority of the deaths have been chalked up to unknown causes. The DNR’s most recent estimate of the northeast moose population – 6,500 animals in 2007 – was down by 23 percent from the 2006 population of 8,400 animals.

“It’s pretty clear the population is in a slow decline and has been for a couple of years, if not longer,” Schrage said. “We’re seeing mortality rates on moose that are substantially higher than what’s average for North America.”
The non-hunting mortality rate of the radio-collared moose was 34 percent last year, and is about 22 percent a year over the course of the study. The average elsewhere is between eight and 12 percent.

During the project, researchers will continue looking at survival rates and trying to clarify what they believe are correlations between climate change and moose mortality.

“This will give us a better opportunity to understand that relationship and to do a better job predicting what effect climate change might have on moose,” Schrage said.

On the ground

While the moose population has declined, researchers “had no shortage of targets” last week to put collars on, Schrage said. By the end of the day Thursday – after less than three days – they had collars on 26 animals in the central Lake County area.

The operation involved work in the air and on the ground. A spotter plane high in the sky located moose and provided the locations to a crew in a helicopter – from Quicksilver Air in Fairbanks, Alaska – that got closer to the moose and shot a dart into them. Once the animals were down, researchers came in and put radio collars on them, attached ear tags, checked body conditions and for evidence of winter ticks, and took blood, fecal, tooth, and hair samples.

Testing of the samples is a longer, more geographically diverse process. A lab in Saskatchewan will test for brainworm; a lab in Virginia will test for pregnancy; additional disease and parasite testing will be done at the University of Minnesota; a DNR lab in Grand Rapids will do blood chemistry work; and a lab in Wyoming will receive the tooth samples to age the animals.

All of this year’s samples will were from cow moose. In the past, both cows and bulls have been collared.
“We’ve learned about as much as we need to learn about the population dynamics of bulls,” Schrage said. With the high mortality rates in the herd, “the future of this moose population depends on the cow moose segment. By focusing entirely on cow moose, we are going to maximize our sample.”

Ongoing study

The study originally was slated as a five-year affair. The first moose was radio collared in February of 2002, but researchers didn’t capture as many animals that year as they hoped. And as the work progressed, researchers started “seeing things that we weren’t expecting,” Schrage said.

The expectation was that wolves, cars, and hunters would amount for most of the mortality.

“All three of those combined aren’t measuring up to what we’re losing to what we’re calling ‘unknown,’” Schrage said.
With funding for the study set to run out, Schrage got a Tribal Wildlife Grant to continue it into 2007. Another more recent grant from the same source will extend the study another three years, and it’s now set to wrap up in February of 2011.

By then, Schrage is optimistic researchers will have nailed down what’s causing the decline and have a better understanding of where the moose herd is headed. While he hopes that will help managers reverse the trend – if, indeed, the decline still is happening then – Schrage doesn’t think it’s too early to take additional action.

“The numbers are trending down and I think we need to be more aggressive right now about trying to reverse that,” he said

Tags: Moose