Friday, February 15, 2013

Why do Nolalu wolves have mange & not Red Lake's?

Timber wolf in Nolalu caught on trailcam shows mange on its tail and back

Wolf near Bow Narrows photographed in October shows healthy coat
My trail camera captured the top photo of a timber wolf a couple of days ago behind our home in Nolalu, Ontario, near Thunder Bay.
If you look closely you can tell that this wolf has sarcoptic mange, a disease that causes animals to lose patches or even all of their fur. You can make out that the wolf is missing a patch of hair right in the middle of its back. Although you can't see much of its tail, the bit that does show looks mostly naked.
By comparison, check out the second photo I got with my trail camera not far from camp last fall. This wolf, and many others I photographed over a couple of weeks, all had superb coats.
Trappers in the Nolalu area all report catching wolves with mange. Most of the ones I have photographed here have shown the disease.
The question is why do they have it here and not farther north? Nolalu is 50 kilometers (30 miles) southwest of Thunder Bay, near the top of Lake Superior. Red Lake is about 350 miles to the northwest.
I haven't heard any biologist comment on the subject but I will hazard a guess myself.
Nolalu has a large population of whitetail deer. The main herbivores at Red Lake are moose.
I'm not suggesting that deer spread the disease of mange. It is actually carried by mites, similar to ticks, and to the best of my knowledge, one diseased wolf infects another.
But here is how deer might be affecting the picture. Where there are a lot of deer, like in Nolalu, there are also a lot of wolves; therefore they have more chance of contact with each other.
In Red Lake, where moose are the main prey of wolves, there are fewer predators. Moose are never as numerous as deer. They are bigger and require larger areas to feed upon. Therefore wolves, or wolf packs, are much less likely to meet each other.
The deer factor also is a reflection of a bigger reality - climate change. When we moved to Nolalu 26 years ago, deer were a rarity; moose were the main herbivores. Today moose are almost non-existent here and deer are abundant.
In that time the winter weather has changed dramatically. It used to be -30 C at night from December to the end of February. Now we might get a single week of such temperatures. However, it isn't really the temperatures that influence deer, it is the snow depth.
Back in the 1980s we would typically have three feet of snow through much of the winter and some years four feet or more. That was just too deep for deer and most of them perished. The taller moose had no trouble. Now the snow depth is usually just a foot or so. In fact, that is what it is here right now. This is no problem at all for deer and their numbers have consequently exploded.
Although deer may not carry a disease to wolves, the same cannot be said about their relationship with moose. Deer carry a parasite called brain worm  that is fatal to their larger relative. That parasite has been proved responsible for the demise of moose in the Thunder Bay area. Nearby Minnesota has just cancelled its moose hunt for 2013 due to progressively lower moose numbers. There is really no reason to think the problem is anything other than expanding numbers of whitetails.
Red Lake, which is also experiencing climate change, of course, has not experienced the reduced snowfall quite as much as Nolalu or Thunder Bay. It still gets, at least on occasion, three feet of snow and has done so again this year. That has kept the deer numbers down and therefore also the wolf numbers.
I think fewer deer mean fewer wolves and fewer chances for the wolves to catch mange.
Climate change in the Thunder Bay area has also meant that more wolves with mange survive. In cold conditions, many of the wolves stricken by this disease would die from exposure.
Incidentally, as if you needed another example of mankind's stupidity, mange is a disease purposely introduced by humans to North America. It was released by authorities in Montana to kill wolves.

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