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Warming North a breeding ground for ticks
Cases increasing in moose populations as temperatures rise, say biologists

Meagan Leonard
Northern News Services
Friday, May 15, 2015

NORTHWEST TERRITORIES
A photo of a mangy moose running across Highway 3 between Behchoko and Yellowknife May 2 has people talking about ticks. And according to regional biologists, the North's warming climate means this could be a sight that becomes more common.

NNSL photo/graphic

A moose infected with ticks. It takes an infestation of around 50,000 ticks to kill an animal. Although moose in NWT typically carry a few hundred at a time, animal carcasses in the south have been found with as many as 100,000 on them. - photo courtesy Dr. Bill Samuel, University of Alberta

An official with the Department of Environment and Natural Resources (ENR) says the number of reported cases has been steadily climbing and though the pests do not yet pose a significant threat to moose populations, he is monitoring the situation closely.

Regional biologist for the North Slave region Dean Cluff says the warming climate is encouraging more moose to move north while also providing a breeding ground for ticks.

"It's warming up so as the moose move into the territory these larvae are surviving," he said.

Cluff says it takes upwards of 50,000 ticks on one animal to kill it and typically infected moose in the NWT are only found to carry few hundred at a time. However, ticks can debilitate an animal making it more susceptible to exposure, starvation and predation. He says he has seen "ghost moose" where all the brown guard, or outer layer, hair has fallen out leaving just the grey under-layer.

"That is a problem if it's still late winter because the insulating value of the hair is gone and then they can starve," said Cluff.

"They also spend a lot of time grooming instead of feeding and so they starve or they're more vulnerable to predation."

Although there is no easy way to alleviate the pests, cold temperatures and forest fires help keep the larvae population under control says Cluff. Female ticks fall from a moose in the spring and lay their eggs in the forest brush. After the eggs hatch, larvae spend the summer there and then latch onto a moose in the fall.

"The only real way to get rid of them would be to put a flea collar on the moose," he said.

"What really does control them is fires, so when you've got eggs or larvae in the ground and a fire goes through that kills them."

If winters continue to get shorter and warmer, the North could face a situation similar to Alberta or Quebec, where hunting bans have had to be put in place as ticks become more numerous.

"In Minnesota, New Hampshire and Quebec the moose populations are getting down to the point where no hunting is allowed," he said, adding moose in those areas can have up to 100,000 insects on them at any one time.

Although ticks have been known to feed on many members in the moose family such as caribou, deer and elk, moose have not adapted to the insects as well as other species and therefore are at the highest risk.

Moose are relatively new to North America. They are believed to have come across the now-underwater ice bridge from Asia only 10,000 years ago, while evidence shows deer have been here for millions of years. This means elk and deer have developed ways to mitigate tick infestations while moose haven't.

"Deer and ticks have been in North America for maybe a million years and evolved together," said Cluff.

"Elk and deer also seem to be able to groom a little bit better and remove those ticks."

University of Alberta professor emeritus Bill Samuel specializes in the influence of parasites on large mammals and says large counts of tick-related deaths in moose have been occurring since the early 1900s.

"In central Alberta in the winter of 1981/82 . many hundreds, like some thousand or more died," he stated in an e-mail to News/North.

"(We) found an average of 82,900 ticks on those moose. That is just under five ticks per square centimetre of skin."

Samuel said if temperatures continue to climb in the NWT this type of scenario - previously unheard of in the North - could be a real possibility.

"If autumns are mild in temperature and snow comes a little later . then the larvae on the vegetables stand a better chance of surviving longer," Samuel said.

"If winters are shorter . when a female tick drops from a moose to lay eggs, more might survive."

Cluff emphasized at this point threat to the territory's endangered caribou population is low, as the animals do not usually spend in exposure areas.

"We don't see ticks on caribou (because) caribou are on the tundra in the summertime . and then they come into the trees in the winter," Cluff said. "Ticks don't drop off until the spring or summer and the caribou have already left - if they were around in the summer it might be more of an issue."

Fortunately, this particular species of tick is not a health risk to humans and do not pass on infections such as Lyme disease, says Cluff.

"It's a one-host tick. It doesn't drop off and go to another host - it always is on the same moose for its lifetime," he explained. "There's no risk . if you handle a moose that has ticks . and it's an external parasite so it doesn't affect the meat in any way - it's still edible."

Cluff says ENR encourages anyone who encounters a moose displaying signs of a tick infestation to report it.

"It's present in the system, it warrants monitoring but it's not a population-level concern at this point," he said.

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