What’s more irritating, black flies or winter ticks?
If you’ve encountered a ghostly-looking moose in spring in Algonquin Park, you may have asked yourself: “Why are the moose missing so much of their fur?” The short answer: winter ticks.
Many biologists believe climate change is to blame for the sudden infestation of winter ticks on moose, and after encountering our share of twig-eaters we have to agree. Shorter winters have created more favourable conditions for these blood-sucking parasites to flourish.
Ontario’s moose population dropped by about 20% in the decade before 2016. In a Vermont study of heavy tick years, fewer than half of the moose calves survived their first winter.
Now, when we’re talking about the “winter tick,” we want to highlight that these suckers are a separate species from the deer and wood ticks we’ve come to know.
Unlike black-legged ticks (deer ticks), which feed on a new host at each stage, winter ticks climb aboard a moose as tiny larvae in the fall and grow into adults on that same moose. Contrary to popular belief, winter ticks don’t carry diseases that can be transmitted to humans and meat from infested animals is still fit for human consumption. Because winter ticks favour a single host, Lyme disease isn’t a concern for humans, however the tick’s 5-month ride can drain moose of enough blood to cause death.
A single moose can carry tens of thousands of winter ticks, and some have been found with more than 70,000! Think about that next time you complain about an annoying black fly.
The resulting moose fatalities are driven by anemia, fur loss, weight loss and infection. These winter ticks irritate the flesh of the moose so much that they can rub so furiously against tree trunks their outer coats disappear, leaving them prone to hypothermia. Moose calves are particularly vulnerable, with each tick swelling to the size of a grape by late March.
Winter ticks mate on their host in early spring. In late March and April, the females, swollen with blood, drop off the moose to lay their eggs on the ground, then die. When they land on snow, few survive long enough to lay eggs. On bare, mild ground, many more do, and thousands of new larvae wait in the brush that fall.
Since 1984, biologists in Algonquin Park have been conducting aerial surveys in the spring to assess the degree of hair loss in moose. Ontario’s Ministry of Natural Resources notes that logging, road-building, predation and hunting have also contributed to reduced habitat and reproduction rates of moose, but more studies need to be conducted to understand the full scope of this issue.
With these shocking statistics on the table, you may be asking, “What can I do to help?"
Ontario Parks suggests reporting your observations of winter ticks through the iNaturalist app. Simply take a photo of the moose, identify or tag your photo with “winter tick,” and describe the amount and areas of hair loss. The more visibility we can have on this issue, the closer we come to finding a solution.
Want to see Algonquin’s moose for yourself, the respectful way? Join us on an Algonquin Park photography workshop, and read our 9 Tips to Avoid a Moose Collision before you drive Highway 60.
Print Resources:
CBC Canada
Canadian Wildlife Federation
The Atlantic
Algonquin Park Moose Hair Loss Survey
The Narwhal
Fishin’ Canada
Radio Canada International
Alces. A journal devoted to the biology and management of moose. Lakehead University School of Forestry, Thunder Bay, Ontario.
Banfield, A.W.F. 1974. The Mammals of Canada. University of Toronto Press, Toronto.
Chapman, J.A., and G.A. Feldhamer. 1982. Wild mammals of North America. Johns Hopkins University Press, Baltimore.
Hoshino, M. 1988. Moose. Chronicle Books, San Francisco.
Jones, H., Pekins, P., Kantar, L., Sidor, I., Ellingwood, D., Lichtenwalner, A., & O’Neal, M. (2019). Mortality assessment of moose (Alces alces) calves during successive years of winter tick (Dermacentor albipictus) epizootics in New Hampshire and Maine (USA). Canadian Journal of Zoology, 97(1), 22-30.
Patterson, B. R., Benson, J. F., Middel, K. R., Mills, K. J., Silver, A., & Obbard, M. E. (2013). Moose calf mortality in central Ontario, Canada. The Journal of wildlife management, 77(4), 832-841.
Samuel, W. M., & Welch, D. A. (1991). Winter ticks on moose and other ungulates: factors influencing their population size. Alces: A Journal Devoted to the Biology and Management of Moose, 27, 168-182.
van Wormer, J. 1972. The world of moose. J.B. Lippincott Co., New York.
