Wednesday, November 6, 2013

warmer climate, more parasites, fewer moose


Thanks To Parasites, Moose Are Looking More Like Ghosts

The news for moose is not good across the country's northern tier and in some parts of Canada. A recent and rapid decline of moose populations in many states may be linked to climate change, and to the parasites that benefit from it.
In Minnesota, moose populations have dropped from a high of more than 12,000 two decades ago to fewer than 3,000 now. Moose in some parts of Manitoba have declined by 50 percent and more.
"The colder the weather, the more moose you're going to see," says hunter Nat Rockwell, as he brings a female moose he bagged in New Hampshire's White Mountains to a weigh station.
The 70-year-old tool and die machinist watches as the moose is hoisted and clipped to a scale. She weighs in at 630 pounds. Rockwell asks New Hampshire's moose project leader, Kristine Rines, to check for ticks.
Though most ticks have already abandoned the moose body, Rockwell's concern about ticks is well-placed. Biologists and hunters around the nation say that declines in moose populations have often been accompanied by a surge of infestations of the winter tick. A single moose can carry more than 100,000 of the bloodsuckers.
Sometimes, Rines says, anemic, infested animals are transformed into "ghost moose."
That happens when the moose "have scratched all winter long trying to get the ticks off, and they break their hair all off, and because the hair follicle is broken you see the white inner portion," she says. "And they literally look like ghosts."
One recent year, nearly every moose calf-tracked by New Hampshire biologists died. Rines says several factors are at work. Those include shorter winters, with less snow on the ground. That helps the ticks, which die if they drop off an animal onto snow, but survive and breed if there is bare ground to land on.
Climate change, Rines says, could spell the fate of the moose in New Hampshire. Not only do shorter winters benefit the ticks, they also benefit white-tailed deer, which act as a reservoir for a parasite known as brain worm. That parasite doesn't harm the deer, but it'sfatal for moose.

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