Warming climate and winter ticks decimating moose populations

BROWNVILLE, Maine — Chris Read is the owner of the Gunsmoke Lodge in Brownville, Maine, and, along with many of his patrons, is a lifelong hunter of Maine’s wildlife, including moose.

But these days, he is worried. Though the state’s last official count of its moose population, in 2012, put the number of moose roaming Maine’s forests and mountains at about 76,000, he no longer believes that is accurate.

“I think the state’s numbers of deer moose are way off,” Read said. “I’m guessing it’s more like 50,000 to 55,000. It’s just my theory, based on sightings. I think the moose population is definitely in decline.”

He is not alone in his fears. Hunters, academics and environmentalists fear that moose numbers across Maine and in other parts of the U.S. are experiencing a worrying decline in numbers in the face of deadly ticks that are decimating populations. And at the root of the parasite problem could be something much harder to control: climate change.

Wildlife photographer Mark Picard is another worrier in Maine. He spends a lot of time shooting moose, although he uses a camera, not a rifle. He knows Maine’s moose so well, he can recognize individual animals by their antlers or fur patterns.

“There has absolutely been a tremendous decline,” he said.“I go everywhere. There are places I used to go and I’d see 10 moose in one spot. Now I am lucky if I see any,” he said.

He doesn’t hesitate to name the main culprit: the winter tick. “I have come across moose carcasses that haven’t yet been claimed by the eagles and coyotes. They have been stripped of most of their fur, so the moose died of hypothermia or loss of blood,” he said.

Studies show that up to 100,000 ticks can be found on a single moose — enough for the animal to scratch off areas of fur and send it to a slow, unpleasant death by a thousand bites and exposure to the elements. The parasites leap onto moose in the autumn, burrow into their thick coats until they find skin and stay attached all winter, engorging themselves on blood. 

When they fall off the moose in the spring, they die if they fall onto heavy April snowpack, but if the winters are short and the ticks fall on warm, bare ground, the females lay eggs and repeat the cycle. And that is where climate change comes in. As Maine’s winters have gotten warmer and shorter, snowpack melts earlier, and tick populations boom, becoming a much deadlier threat to moose.

Lee Kantar is taking a more scientific approach to Picard’s anecdotal evidence. Kantar is the moose project leader for the Maine Department of Inland Fisheries and Wildlife. He tracks 46 collared moose that are outfitted with GPS and other sensors. When a moose dies, Kantar gets emails from the collar.

“When there has been no movement for six hours, the collar transmits GPS location, and I go try to determine cause of death,” he said.

He doesn’t deny that winter ticks are wreaking havoc on moose. Tying it specifically to climate change, however, he said, is something that will take longer to confirm.

“Figuring out how it is all connected to climate change is what will take time." But, Kantar acknowledges, "there is a link between climate moderation and winter tick numbers.”

New Hampshire Fish and Game wildlife biologist Kristine Rines, however, is more emphatic in her indictment of climate change.

“There’s no question in my mind that climate change is a big factor … By and large, our winters are three weeks shorter than they were 20 years ago,” she said.

She added that the climate affects two parasites, both which play big roles in the health of a moose population. The decline in moose numbers leaves an opening for more white-tailed deer, which bring in more brain worm, which is also lethal to moose. In some states, studies are being conducted to see if warmer weather is having an impact on moose by raising their body temperatures, but results of those studies are years off.

“The bottom line is these two parasites are killing them, and we can prove it," Rines said.

The proof isn’t pretty. Of 27 collared calves in New Hampshire, 20 succumbed to winter tick; one yearling and one adult also died. In neighboring Maine, 21 of 35 collared calves fell victim.

Perhaps ground zero for the moose die-off has been Minnesota. Generally shorter and warmer winters (2014 excepted) have made the state a petri dish for winter ticks. In Minnesota robust moose populations used to inhabit two portions of the state. The northwestern population 20 years ago numbered 4,000. 

And today? “They’re gone. To go to nothing in two decades, that is what is scary for us,” said Michelle Carstensen, the wildlife health program supervisor at the Minnesota Department of Natural Resources. There may be several dozen moose still roaming the vast northwest of the state, but the department no longer tracks them there because, she said, the population has essentially been “extirpated.”

“We could be facing the same situation in the northeast. We are not sure if the number will stabilize or keep tanking,” said Cartensen, who puts the state’s remaining moose population at 3,500. That number is down 60 percent from 10 years ago, she said.

In 2013 moose registered a 19 percent mortality rate in Minnesota, far above the 8 percent average in a healthy population. In 2014, aided by a cold winter, that number dropped to 12 percent.

Determining that the moose die-off is tied solely to climate change is something that Cartensen also isn’t ready to do yet.

“The balance is really tricky. There’s no smoking gun. It seems to be a very complex set of factors,” she said.

In Maine, Kantar continues to follow the data, even if that means moving at a slower pace than some would like. Like Cartensen, he wants more time and more data before drawing a definitive conclusion about cause and effect.

“What is the role of winter tick over time? The answer: We don’t know. We have had winter tick going back until at least the 1930s. The biggest question: When you have a bad winter tick year, how frequent are those years?” he said.

He said the data are just too new to extrapolate long-term trends.

“Everyone wants to know, ‘How many animals?’ And if you can’t answer the question, you aren’t doing your job. But the amount of resources required to estimate a population of animal in a state this big is immense,” he said, adding that risky, expensive helicopter flights and lots of personnel would be needed.

Dennis Beaulier is the owner of Gate Way Variety in Ashland, on the edge of the thick North Woods of Maine. The Gate Way is a tagging station, and he said that while moose numbers have been down the past few years, the moose population “seems to go in cycles.” He can remember years in his youth when it seemed moose numbers were not as high either. “Their numbers will come back.” 

Meanwhile, Picard will continue to spend his time photographing and documenting these docile creatures — if he can find any. “They aren’t dumb. People call them swamp donkeys, but they are a wicked smart animal for what they are … They are pretty adaptable and survive in almost any conditions.”

But as winter turned to spring in Maine and road signs warned motorists of moose, he said he hadn’t seen one in months. And a friend of his who grooms snowmobile trails hadn’t seen one all winter.

“Maybe these things just go in cycles,” Picard said. “I’m hoping one day the moose will come back.”