Ready to tackle a squeamish topic that could make your skin crawl?
Given I have limited space, I’ll dispense with pests – like moose flies that tailgate their warm-blooded host for much of the snow-free period – and focus on the known agents of disease in moose that are suspected of significantly impacting moose populations.
That would be parasites. Virtually all wild animals have parasites in their bodies, but few are diseased. The truth is that parasites are everywhere and they are living inside most of us (90 percent), regardless of where we live or the size of our girth.
For moose, the list of parasites gets pretty long… and believe me when I say moose harbor some very creepy companions; most of whose hideous appearance can only be “appreciated” under the magnifying eye of a microscope.
While a moose can be trained to step onto a weigh scale and have blood samples drawn, let’s just say it’s not the easiest method to study the effects of parasites and disease on large moose populations.
The recently implemented DNR research study using collars rigged with satellite communications technology, on the other hand, appears more feasible. Monitoring 173 moose in the Arrowhead region, researchers found, of the 47 moose autopsied so far, 66 percent died from infection, parasites or illness.
Michelle Carstensen, Wildlife Health Program supervisor for the Minnesota Department of Natural Resources, who has been with the agency for 13 years, estimates that 21 percent or more of the moose in Minnesota are dying from brainworm, a parasite known as Parelaphostrongylus tenis (you’ll never see this on “Wheel of Fortune”), or are vulnerable to wolves because of it.
Moose experts Dr. Murray Lankester, Department of Biology, Lakehead University, Thunder Bay, Ontario and William Samuel, Alberta Animal Health Division, maintain P. tenis has the potential to significantly impact moose populations.
Brainworm or “moose sickness,” as it is commonly referred to, was identified as early as 1912. One of the earliest descriptions of sick moose seen in Minnesota and in Quetico Park of Ontario was characterized as “blind, aimless wandering, staggering, bumping blindly into perfectly obvious obstacles, weakened condition, paralysis . . .” (why am I all of a sudden feeling a bit self-conscious?)
Some 50 years elapsed from the time of the first reports of the disease until the cause of moose sickness was finally determined in 1962 by Dr. Roy Anderson, a biologist with the Ontario Research Foundation. Anderson determined brainworm was killing moose, and that white-tailed deer were the carriers.
Patrick D. Karns, former research biologist with the Minnesota Department of Natural Resources, Grand Rapids, Minnesota, suggested that high densities of infected deer were responsible for a major moose population decline in Minnesota in the mid-1920s and early 1930s.
Our neighbor to the east, Michigan Technological University researcher Rolf Peterson, claims brainworm is one of the primary reasons moose are declining on the mainland.
It is not insignificant to note that Newfoundland – similar to the island geography of Isle Royale – does not have any whitetail deer.
Hold this thought, for the moment . . .
Another one of the most insidious parasites that threaten moose populations is the “winter tick.”
All right, the moment’s up . . .
The winter tick does not occur in Newfoundland. Why? No whitetail deer… and Newfoundland is fortunate the winter tick was not imported when the moose were brought to the island in the late 1800s.
It is believed, in the beginning of the ’90s, nearly half of Minnesota’s 6,700 moose died over a two-year period as a result of a “winter tick” infestation.
William Samuel, in a research study conducted in the early ’90s, estimated the average number of ticks per moose to be 32,500 or 9.23 ticks per square inch; 39 of the 212 moose tested had more than 50,000 ticks. (Okay, now my skin is beginning to crawl.)
Dave Ingebrigtsen, DNR area wildlife manager here in Grand Marais, commented in a February 2016 Star Tribune article, written by Dennis Anderson, on the DNR’s proposal to hold deer numbers down in NE Minnesota in an effort to help moose, “There’s no smoking gun that deer are the primary problem. But there’s enough evidence … so it kind of makes sense to do it [keep deer numbers low in moose country].”
Added Tom Rusch, area wildlife manager in Tower: “This is a moose emphasis area, and from my perspective, we’re making the best decision with the best science we have right now.’’
Meanwhile, Patrick Whittle, writing in a June issue of the Washington Times, reported Maine Department of Inland Fisheries and Wildlife officials said it is planning to offer more than 65,000 deer permits this year, an increase from last year’s total of more than 45,000, which itself was a 60 percent climb from the previous year. “Controlling the deer population helps with public health issues such as preventing the spread of tick-borne diseases,” said Ryan Robicheau, a wildlife management section supervisor with the state.
Dr. Lankester acknowledges, “In some areas managed largely by hunting, deer and moose numbers can remain fairly stable over a decade or so. In others, as deer increase in number, moose decline, and when deer decrease, moose increase.”
Observation: If we are serious about keeping our moose here in Minnesota, the challenge remains to measure and comprehend fully the significance of the role played by parasites and diseases in these interrelated living systems. Next week: The influence of predators on the moose population.
Former Cook County Commissioner Garry Gamble is writing this ongoing column about the various ways government works.
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