Widespread drought affecting Minnesota's wildlifeby Tom Robertson, Minnesota Public Radio
DETROIT LAKES, Minn. — The heavy snow that fell on parts of central Minnesota over the weekend may be too late to help relieve widespread drought.
More than 80 percent of the state is in severe or extreme drought, and climatologists say with the ground now frozen, most winter snow will run off into rivers and lakes next spring, providing little relief for the state's parched soil.
Beyond that, there is evidence that the drought is affecting Minnesota's wildlife as they head into winter. Some say that is another sign of how climate change is affecting the state.
In a state wildlife management area just a few miles northeast of Detroit Lakes, for example, a frozen wetland is a lot less wet than in previous years. Drought left the pond smaller than before.
"This beaver pond here is about a three-acre basin, and up until just a couple of seasons ago, this was full of water," said Blane Kelmek, a wildlife supervisor for the state Department of Natural Resources. "And this beaver lodge that we're approaching right now was an active beaver lodge."
Now the beaver lodge is empty, and instead of water there's bare ground. When water levels dropped dramatically, the family of beavers that lived in the wetland probably migrated across land to a larger pond or lake, a move that made them vulnerable to predators.
Klemek said that's just one example of how the drought is affecting the natural landscape. Although drought can improve a wetland by allowing some plant species to regenerate, it is hard on reptiles and amphibians. The northern leopard frog, for example, needs wetlands to wait out the winter season.
Last spring there were reports of hundreds of frogs dying off because water levels were too low.
Dry conditions also have affected food sources for many animals, among them the American black bear.
Bears typically spend most of the summer and fall fattening up for hibernation, Klemek said. But this fall, foods like berries, fruits and hazelnuts were less abundant.
"Bears probably went into their dens and such probably not in as good of condition as they normally would ... and might be coming out in the spring malnourished," he said. "And that could have an effect of course, on a local bear population."
Klemek said many animal species are dealing not just with drought, but with more long-term changes.
"It's been a good decade since we've had real harsh winter weather, and wildlife is responding," he said. "When, for example, winters are tough up north, we might see an influx of owls, certain birds like, oh, the purple finches and common redpolls coming down from Canada when winters are harsh. We're not seeing a lot of that."
Klemek is seeing more birds like the northern cardinal and the red-bellied woodpecker. Both are species that normally wouldn't live this far north. DNR officials are working on a set of plans to deal with the effects of climate change on natural resources. An internal report released last year lays out goals for responding to what's happening, according to Keith Wendt, science policy manager for the DNR's division of operations services.
"One of the first things we did was begin to look at how vulnerable those plants and animals are to a changing climate, so we could channel our resources towards those that we feel are going to be the most threatened by a changing climate," he said.
Minnesota's average annual temperature has increased nearly 2 degrees since 1895. Scientists say that warming is accelerating. Average annual temperatures are projected to rise another 5 to 9 degrees by the end of this century.
The DNR report points to other changes. Ice is forming later and breaking up earlier on Minnesota lakes. Warm water fish like largemouth bass and bluegill are becoming more common in northern lakes, while a coldwater fish species called the cisco has declined 42 percent since 1975.
A whole group of northern tree species, which includes aspen, spruce, paper birch and sugar maple, appear to be receding their range northward by about six miles per decade, the report notes.
Minnesota's drought conditions are likely to become more common, according to Mark Seeley, extension climatologist at the University of Minnesota. He said more of Minnesota's precipitation comes in the form of thunderstorms. That means rain is increasingly being dispersed unevenly, leaving some areas very wet and others very dry.
"I think it's symptomatic of a climate change pattern that is with us now into the future, and is not going away," Seeley said. "I think that is going to be the nature of our precipitation more and more as we go into the future... So we're going to see more and more years ahead that are about great disparities on the Minnesota landscape."
That's a landscape that could look very different decades from now, as species either adapt to the changes or disappear.
- Morning Edition, 12/11/2012, 6:20 a.m.