High-tech tracking moose

[Lee Borgersen]


                  High-tech tracking
8/29/15
 
New remote monitors giving researchers better insights than ever before possible.
 
 
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REGIONAL— New technology has helped wildlife managers gain a better understanding of the reasons behind the decline in northeastern Minnesota’s moose population. That was just one of the messages delivered by Dr. Michelle Carstensen, a DNR wildlife biologist who keynoted the recent annual meeting of the Lake Vermilion Sportsmen’s Club.

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Thanks to the development of high-tech devices, biologists can track the movements of their research subjects to a degree never before possible. At the same time, they can monitor other critical factors, such as heart rate and body temperature through tiny internal monitors, and the data can be recovered remotely via satellite.

The new technology has made it possible for moose researchers to detect within a matter of hours when a moose has died and to send a recovery team out to the site, usually within 24 hours. That typically allows researchers to determine if a moose was the victim of wolf attack, or if it died of health-related causes. It also allows the researchers to recover the moose carcass for necropsy, to help determine the health status of the animal at the time of death.

The technological improvements have come just as researchers are trying to understand the reasons behind the ongoing moose decline in northeastern Minnesota, a trend that has now been detected in several other northern U.S. states and some Canadian provinces as well. While the reasons behind the widespread declines in North America likely vary depending on location, here in Minnesota, it’s a combination of disease and wolf predation that appears to be behind the decline.

The good news, if there is any to report, is that the mortality rate of the roughly 100 adult collared moose in the joint state, federal, and tribal study appears to have improved. Last year, the mortality rate for moose in the study was 11 percent. That’s well within the eight-to-12-percent annual mortality rate typical in North America, and it compares very favorably with the 21-percent mortality seen during the first year of the study. So far in 2015, only nine percent of the moose have died. While that number could well change in the remainder of the year, adult moose mortality is typically quite low in the fall and early winter. While the latest figures are encouraging, Cartensen said it’s too early to say that the population decline may have stabilized.

Carstensen speculates that the last two severe winters may have improved moose survival by reducing the numbers of whitetail deer and winter ticks on the landscape. Deer carry both liver flukes and the parasitic brainworm, both of which can be fatal to moose. And winter ticks, which can attach themselves to moose by the tens of thousands when abundant, can cause severe skin irritation, loss of fur, and anemia, all of which can prove fatal as well.

Carstensen said she expects to see more winter tick problems with moose this winter, since last spring’s early snowmelt likely allowed more winter ticks—which typically drop off of moose in April— to survive.

Many of the disease factors affecting moose appear to have a connection to climate change, but it’s increasingly clear that’s not the full story. Cartensen noted that while all types of disease combined appear to claim a slim majority of adult moose, wolf predation is the single largest cause of moose deaths. According to Cartensen, confirmed or suspected wolf attacks accounted for 16 of 41 (roughly 40 percent) of adult moose mortalities during the course of the study so far.

“Wolves and health are both affecting the prime age moose,” said Carstensen.

Wolf predation remains, by far, the largest cause of moose calf mortalities, however, and that has significantly reduced the recruitment of younger moose into the population. Of the moose calves collared for the study, that weren’t abandoned by their mothers, 68 percent were killed by wolves, with another 16 percent killed by bears. “We’re seeing a lot of predation,” acknowledged Carstensen, although the calves sample size is extremely small.

The researchers didn’t collar any moose calves this year because of Gov. Mark Dayton’s executive order, issued in early May, that discontinued moose collaring for now out of concern for the high rate of moose mortality and calf abandonment. But Carstensen noted that the research team was still able to recover a number of dead calves by monitoring females for unusual movements. She said mother moose have a typical response to threats to their calves and those movements have alerted researchers to likely calf deaths. While the approach leads to more uncertainty about the causes of calf deaths, she said the team has been able to classify 55 percent of calf deaths as wolf predation, with bear predation accounting for eight percent.

She said the life of a moose calf tends to be short in the wild, at least here in Minnesota. “Forty percent die in the first 30 days,” she said. “Some calves are still surviving, however,” she said.

The information gathered in the research is useful, said Carstensen, in developing management options for the moose going forward. With the hunting season already suspended, she said decreasing deer numbers in the moose range is one option. Predator control is another, but with the timber wolf back under federal protection, that doesn’t appear to be an option, at least in the short term. And given public attitudes, the prospect of DNR sharpshooters taking out wolf packs from the air—which is one of the most realistic options of providing predator relief to moose— would likely be politically difficult, if not impossible. She noted that some Canadian provinces have designated moose recovery zones, where predator control and aggressive deer harvests are used to help moose populations improve. Cartensen said it will be valuable to see if such management approaches are successful. “If I could be commissioner for a day, it would be really cool to try what they’re doing.” But Carstensen said she’d want to be able to radio-collar more moose to be able to better determine the success of the management approach.

Cartensen said the current ban on moose collaring prevents the study team from adding to its current study population, which will gradually disappear over the next several years as individuals die or the collars drop off or cease functioning.


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