Earthwatch teams document wildlife population declines at remote national park.
Earthwatch Institute, Maynard, MA, 14 March 2007 - A plague of ticks, stifling hot summers, and relentless pressure from wolves have driven the moose population on Isle Royale National Park to its lowest ebb in at least 50 years. This summer, Earthwatch teams will continue to monitor the population on this wilderness Lake Superior archipelago.
Moose numbers have sunk from last year's record low of 450 down to 385, the lowest since researchers began tracking their numbers on Isle Royale. Now in its 49th year, 20th year with Earthwatch support, the project is the world's longest-running study of predator-prey relationships.
"Along with this is an even more impressive decline in wolves, from 30 to 21," said John Vucetich, an assistant professor at Michigan Technological University. "The main reason is a lack of food." For wolves, that translates into a lack of moose.
In 2002, the island was home to more than 1,000 moose. Since then, unusually warm summers have dealt a double whammy to the big herbivores: They lose their appetites and seek shelter from the heat, putting them in a worse position to survive winter. And the climate change also seems to favor ticks, causing a massive infestation that has yet to abate.
Fortunately for human visitors to the island, the ticks have no interest in people. A single moose, however, can host tens of thousands at a time, and each tick can suck up about a cubic centimeter of blood. Rather than browse, the moose scratch themselves against trees or bite their hair out trying to remove the parasites. Weight and blood loss often prove deadly.
Wolves are responding to the dwindling of their food supply as they have in the past: with conflict between packs. Last year, Vucetich witnessed members of the island's East Pack attack and kill the alpha male of the neighboring Chippewa Pack. This year, they got his widow, the alpha female.
"All we found were the skull and a radio collar," said Rolf Peterson, a research professor of wildlife ecology at Michigan Tech, and principal investigator of Earthwatch's Moose and Wolves project. "It was nice they left the skull; foxes tow them around, and we might never have found anything."
The pair that were killed were founders of the Chippewa Pack in 2000, when the female was chased off by another pack then nursed to health by a lone male. In the years hence, the happy couple had raised seven litters of pups. "That's way above average in terms of progeny," Peterson said. "She's the number two all-time breeder in the study."
"Amazingly, the Chippewa Pack has hung on; they are now under new leadership," Vucetich said.
But the hard times for wolves are also cascading down to other carnivores. With a shortage of moose meat, wolves are consuming virtually every morsel. For instance, from one 900-pound moose, all that remained was a couple of bones. Even the skull was eaten. Thus, almost nothing is left for smaller predators and scavengers. "Foxes are having a very hard time," Peterson said. "Hares are at a cyclical low, and there's very little left for the foxes to scavenge."
Yet, in the midst of great privation, there are indications that a new pack may be forming. One moose pair is showing territorial signs, scent marking, and has killed about three moose. "It doesn't really count until they breed, but it's kind of interesting that in the middle of all these hardships, they are setting out on their own," Vucetich said.
The Isle Royale wolf-moose study is funded by the National Park Service, the National Science Foundation and Earthwatch. Teams of Earthwatch volunteers have been assisting Peterson's research on Isle Royale for 19 years, monitoring trends in moose kills and winter-starved animals by bushwhacking through the forest in search of their remains.
"Since 1988, Earthwatch volunteers have provided essential physical and financial assistance to the wolf-moose study each summer at Isle Royale," said Peterson. "Summer fieldwork provides information about the genetic make-up of the wolves and tells us the condition of the moose population on which the wolves rely."
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