Winter ticks latch onto Utah’s moose
Researchers study the effects of the ticks on moose populations
April 18, 2017
Since their migration into Northern Utah in the early 1900s, moose have become an iconic image for communities along the central Wasatch Mountains.
But a moose sighting on Main Street in Park City last week revealed a grim fact about the area's most beloved species: they are beginning to show signs of excessive grooming to shed winter ticks.
The two moose in Park City garnered significant attention from the community during their mid-day stroll, but not because of their presence. The animals' dark brown fur appeared scraggly and bare, displaying hairless or white patches, causing concern for many residents and wildlife advocates.
"Those moose are showing signs of excessive grooming because they are rubbing and scratching to shed those parasites," said Dan MacNulty, associate professor of Wildlife Ecology at Utah State University. "What you are seeing when you see a moose walking down Main Street in Park City that has no fur is a manifestation of the natural environment."
Winter ticks will attach themselves to moose by the thousands, causing significant blood loss and, often, higher mortality rates among calves because of the significant blood loss.
In 2013, Utah State University and the Utah Division of Wildlife Resources took a cue from researchers in New England and began studying the effects of winter ticks on Northern Utah's moose population.
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MacNulty said researchers in New England were noticing a dramatic decline in the population because of the parasite. According to an article in The New York Times, researchers in New England discovered "ticks have killed about 70 percent of the calves they have tagged in certain regions, an indication that the tick is taking a significant toll."
Researchers with Utah State University and the Utah Division of Wildlife Resources have been tracking more than 200 moose between the North Slope of the Uintas and the area east of Daniel's Canyon between Heber and Park City.
"Ironically those ghost moose, if you want to call them that, seem to be surviving and the moose that are not grooming or are grooming less are the ones that might be suffering the most from tick loss because those ticks remain on the animal and they continue to loose blood," MacNulty said. "And we are talking tens of thousands of ticks on the moose."
MacNulty said researchers focused on those two areas because they present two different types of habitats.
"The area from Park City basically southeast is more atypical moose habitat with a lot of shrub and Rocky Mountain Maple, not what you would really consider moose habitat," MacNulty said. "What we wanted to address was whether the moose in that habitat are surviving as well as those on the North Slope."
When researchers tracked tick densities on the moose, MacNulty said they discovered that moose in the Wasatch area between Park City and Heber City had higher levels of tick infestation than those on the North Slope.
"That is consistent with habitat difference because the North Slope has more snow and Wasatch is slightly lower, drier and it is a more arid environment and ticks have an easier time in that environment," MacNulty said. "There is a relationship between tick population numbers and winter conditions. The more mild, less snowfall you have, the more ticks you will have in the environment."
MacNulty said the heavy infestation people are beginning to notice on moose is the "lag-effect of environmental conditions." He said this spring will determine how many moose are tick-infested next winter.
"Those ticks fall off the moose and let's say they hit dry ground and they reproduce and in the fall they will gorge on those moose through the winter and at the beginning of next spring," MacNulty said. "That is where you start to see evidence of heavy infestation and potential mortality."
The relationship between ticks and moose is determined by the winter climate, MacNulty said. He added, "There isn't much we can do about winter climate conditions either."
"If those trends continue and increase, the expectation is that we will have fewer moose and people can expect the moose to eventually disappear with the changing climate," MacNulty said. "People need to be aware of that. The decline of moose is a potential casualty of climate change and there is no doubt about it because they are seeing evidence of this in Minnesota and New. Hampshire.
"The overall trend in the population number doesn't, at this time, indicate any sort of imminent collapse," he said. "But the conditions are ripe for a decline."