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Study challenges songbird protection efforts

A 10-year study of birds in the region has come up with some surprising conclusions about the effects of logging on song bird populations. It seems that logging companies who are trying to minimize their impact on the forests by making several sm...

A 10-year study of birds in the region has come up with some surprising conclusions about the effects of logging on song bird populations. It seems that logging companies who are trying to minimize their impact on the forests by making several small cuts instead of fewer larger cuts are having a detrimental impact on the birds. It would be better, says JoAnn Hanowski, research fellow in avian ecology at the Natural Resources Research Institute, to have larger cuts.
"Forests are being chopped into smaller and smaller pieces," Hanowski said. "Roads make corridors for predators. Predators only tend to penetrate so far into the forest. They usually concentrate their efforts right along the edge. Birds that nest further into the forest, away from the edge, have a greater success."
But roads left by logging companies are an invitation to predators like fox, raccoon, fishers and martins. Hanowski noted that while the population of some ground nesting songbirds is decreasing, the population of these predators is increasing. "We need to start varying the sizes of cuts because there are animals that need bigger disturbance areas," Hanowski said. "All this small harvesting, even though it's more appealing to the public, in the long run it's probably not good for most birds."
Cats are also notorious bird predators. A recent study in Wisconsin determined that cats in that state are responsible for killing millions of birds each year.
Of the birds that are declining in the area, Hanowski says they have one thing in common. "Overall, there's four or five species that are declining across the state and the region, and the thing that they have in common is they are ground-nesting birds. We think there may be a link between the increasing numbers of predators and the decrease in the number of ground-nesting birds." 20 percent of breeding birds in this area put their nests on the ground.
Hanowski's findings that ground-nesting songbirds are declining are a concern to her. She says it's too early to draw final conclusions into the cause, but that the combination of increasing numbers of predators and increasing access on logging roads seems to add up. "It does all fit together," she said. "Maybe in five years all these species will go back up, and we'll say, 'Well, that wasn't it.' But right now, it seems to fit."
Hanowski and her colleagues collect data on the birds in Superior National Forest, Chippewa National Forest and the Chequamegon-Nicollet National Forest. Data collection takes place in May, June and July, the three months when the birds are most active. There are 150 forest birds in the state. "We're just figuring out how the birds are doing," she said. "Are their species going up? Are their species going down? Which species are they, and then we try to figure out why. That's the hard part."
A parallel study of forest habitat helps them with part of the picture. But other things happening in another part of the world may be affecting the population changes. "Effects may be something we're doing here," she said, "but it also could be something that's happening in the tropics where they winter or it could be something that's happening on their migratory route. It's a real complicated puzzle. We're trying to fit all the pieces, and figuring everything out takes a long time."
Whether it's natural predators or a natural disaster, like the storms that flattened much of the Boundary Waters Canoe Area Wilderness, bird populations will show the effects. "There's going to be a lot of birds displaced," Hanowski said. "And it's a big enough area to have an effect on local populations. We may lose reproduction from a large number of birds."
Woodpeckers, on the other hand, will find plenty to do in the BWCAW. The dying trees and the insect population will likely result in a large increase in the number of woodpeckers. Other birds who frequently inhabit an area right after a forest has been affected by storms or a large fire will also find happy hunting grounds in northern Minnesota this summer. "It's not like there won't be anything there," Hanowski said. "It's just going to drastically change the composition of the (bird) community."
"(Birds) are very important in terms of keeping forests healthy," Hanowski said. "They eat a lot of insects. All those insects eat the trees. If the birds weren't there and the insects were eating the trees, it would really decrease the productivity of our forests. So, they're very important ecologically."
Since backyard bird feeding has become more popular, Hanowski says the population of permanent residents, those birds that winter in the area like chickadees, nuthatches and woodpeckers, are increasing. "Obviously, if you supply food for birds in the wintertime when there's normally a crunch in terms of the amount of food out there, you're going to increase the population," she said. "And we've been seeing that."

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