Moose
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What causes a moose to have patchy fur?

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This spring, we saw a moose with an unusually patchy, scraggly coat. It looked very mangy. What causes this?
—Danny Poe, via e-mail

Well, it might be mange. Or it’s possible you saw a moose that was shedding its winter coat (spring is not the prettiest season for these ungulates). But it sounds like you’re describing a moose with a winter tick infestation.

Winter ticks are a different species than the familiar Lyme-disease-spreading blacklegged (or deer) ticks that we all worry about in the summer. They’re larger, prey on hoofed mammals such as moose, deer, elk, caribou, and horses, and feed off their hosts during—you guessed it—the winter.

Winter ticks have only one host during their lifetimes. The larvae attach to an unlucky moose in the fall, mature into adults, and stay there until the spring (late March to early May), when they detach, and then die. A minor tick infestation might not affect a moose much at all, but a severe case will drive it to groom aggressively (licking and biting itself, and rubbing against trees), which causes excessive hair loss. Usually this is concentrated at the head and shoulders, but the moose can lose fur from anywhere that it rubs. Along with having a patchy coat, tick-infested moose are often thin, because they abandon normal feeding behaviour and spend more time grooming instead.