Ticks Are Killing An Alarming Number Of Moose Thanks To Climate Change

Known as “ghost moose,” this adult moose illustrates typical hair loss associated with high loads of winter ticks. (Photo: Dan Bergeron, N.H. Fish and Game Dept.)

The horrifying effects of climate change are evident seemingly everywhere you look. Now, a report from researchers at the University of New Hampshire (UNH) suggests that climate change favourable to a parasite is impacting the moose population in New England. According to their findings, winter ticks that gorge themselves on a moose’s blood by the tens of thousands during the fall and winter were responsible for killing roughly seven in 10 moose calves over the course of the three-year study.

The researchers, who have been studying the calves in New Hampshire and western Maine since 2014, published their findings in the Canadian Journal of Zoology in September, with UNH publishing a press release on the research this week. During each of those three years, the team examined 179 radio-marked young moose for parasites and their condition over the course of a four-month period. Of those calves they screened, 125—or nearly 70 per cent—of the moose calves died. The researchers suspect this is primarily because of the winter tick.

“The iconic moose is rapidly becoming the new poster child for climate change in parts of the Northeast,” Pete Pekins, a professor of wildlife ecology at UNH and a lead author on the study, said in a statement. “Normally anything over a 50 per cent death rate would concern us, but at 70 per cent, we are looking at a real problem in the moose population.”

The problem is that winter in the area seems to be increasingly delayed as the result climate change, making for longer falls and earlier springs. This is favourable for the tick, which attaches to the moose in the fall and feeds on its blood through the winter before detaching in the spring.

“Most people have heard of ticks and are concerned about Lyme disease,” Perkins said last year in UNH video about the team’s research. “Let me just say that this is a different tick. Part of the story here in New England as the slow effects of climate change have taken hold are winters are starting later and later. Our first snowfall is key to stopping how many ticks can get on a moose.”

The study reported that 88 per cent of mortalities of the tagged calves were associated with “moderate to severe infestations” of the parasite, with the ticks causing emaciation, anemia, and blood loss. Each moose calf had roughly 47,371 ticks on average. But that’s not even as bad as cases can get. In one case recounted to the New York Times, researchers observed a dead moose calf with about 100,000 ticks—though that number was likely even higher before parasites detached after it died. Pekins told the Times that tick numbers over 35,000 are “trouble for a calf moose.”

While researchers observed that conditions were slightly better for adult moose, and most survived, they too showed signs of poor health with anemia and blood loss. The ticks may be affecting their breeding patterns, as well, by impacting their reproductive health.

“The moose are being literally drained of blood. This is about as disgusting as it gets out there,” Pekins told the Boston Globe last year.

This is not the first we’ve heard of the declining moose population in New England. News of the team’s research, which is the largest survey of New England’s moose population ever, was reported as far back as 2015, at which time the specific cause and scope of the deaths wasn’t clear.

It’s not just the moose who have been affected by the area’s tick explosion. In addition, the overall number of non-moose ticks (which rarely bite humans) has spiked in the last decade, according to the Associated Press last year, leading to a rise in cases of tick-related diseases in people living in the New England area.

[Canadian Journal of Zoology via UNH]

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