Mike Groll  /  AP
A deer mouse has a monitor attached to her ear at the Adirondack Ecological Center in Newcomb, N.Y., last Wednesday. Scientists are tagging some mice to study why the region has seen a boom.
updated 10/5/2007 3:29:51 PM ET 2007-10-05T19:29:51

At the general store on Canada Lake in the southern Adirondacks, mice were the talk of the town this summer. With winter closing in, people can expect to keep hearing the skritch of tiny feet as the destructive rodents move indoors.

"My husband was buying mousetraps at the store and three people said, 'Do you have mice too?'" Mary Cannon said. "We have over 300 families on the lake and I'll bet every one has been affected sometime this summer from excessive mice."

A big berry and seed crop, easy winter and, perhaps, fewer predators have helped mice and other small critters thrive this year, researchers said.

"It's kind of the perfect storm, if you will, for mice this year," said biologist Charlotte Demers, who traps them live, releases and studies them. "We're not talking plague proportions here or anything, but I think it was enough that we've gotten phone calls from a lot of local people: 'What's going on with the small mammals this year? They seem to be everywhere.'"

Cannon, secretary of the lake association, said she's been relatively lucky since there is a basement in her year-round home on the lake about 50 miles northwest of Albany. She's had only about a dozen mice. She'd notice droppings, set a trap and catch one. Her neighbor, with more of a seasonal camp, had three or four a day before she left for Florida. Some other people said they had more.

"We've been up here 12 years. My husband's been up here about 45 years. We've had mice before, but not like this," she said. "My sister-in-law lives down the lake. They took over her house in the winter. They basically moved in, which she's never had before."

That led to a good bit of speculation about why now, questions to Cornell Cooperative Extension and finally an answer from state biologists 60 miles farther north in Newcomb, where they've been watching small mammals since the 1950s.

Food, weather factors
At the Adirondack Ecological Center, run by the State University of New York College of Environmental Science and Forestry, Demers and other scientists say a high yield from beech trees, oaks, hickories, maples and conifers has helped propel the mouse population. She adds in the rodents' high reproductive rates — four to six litters a year — along with a mild winter and dry spring boosting survival rates. And there may be fewer predators.

The SUNY-ESF biologists began live trapping in 1992. This year, they've caught 19.2 mice per 100 trap nights, double the next highest year's rate.

"The other small mammal we're seeing a big jump in is the red-backed vole," Demers said. It's another small rodent that eats vegetation and seeds and, like mice, stays busy above ground in winter.

After some tough years for the 22 species of small mammals in the region, the ranks of predators like foxes, coyotes, hawks, owls, bobcats, weasels and snakes probably decreased slightly, and it takes them longer to bounce back, Demers said. With more food around, they probably will rebound, she said.

Meanwhile, seed production is dropping off this year. The rodent population is likely to follow. Also, disease is damaging many beech trees in the region.

"It's a tough life up here," said Demers, who has spent the past 21 years studying wildlife in the central Adirondacks. "I don't think we ever really see large populations of predators because of the winter. It's the big unknown, the limiting factor. The winters we have seem to keep everything in check."

'Worse before it gets better'
Perhaps less so for the mice living near people and now heading indoors.

"If you're a homeowner, I'm pretty sure it's going to get worse before it gets better," Demers said. "Now is the time of year they're looking for places to cache their food."

The general store in Newcomb recently added a note in its electronic newsletter that it had mousetraps. Some hardware stores had run out.

Department of Environmental Conservation wildlife biologist Gordon Batcheller said there's some anecdotal evidence elsewhere in the state for good crops of grasses and seeds and high populations of small rodents.

"It's probably hard to make a generalization for the entire state. You have micro-climates and micro-conditions," Batcheller said.

He said the problem for homeowners is that mice enter through openings as small as one-quarter inch and can proliferate despite living only months. Later, others will follow the same mouse scent into the house.

"They're essentially pregnant all the time and breeding all the time," Batcheller said. "Frankly, every home, whether it's a $10,000 shack or a $10 million mansion, at some point they're going to have mice in the house. "

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