A piece of wooded land near our home is being developed. This stand of mature trees is a remnant of the Big Woods that once covered much of east central Minnesota. Trees that are 200 years old have been removed to create homesites.

The owner could not maintain the land, so chose to sell. That’s understandable.

There are about 30 acres of old trees there, a woods deeply shaded in the summer, the darkened understory so thin that walking is unimpeded. I once spent a lot of time there. It’s beautiful, but not particularly birdy; old woods tend to be that way.

It has been heavy on woodpeckers, chickadees and nuthatches. Owls have nested there, and red-shouldered hawks. Wild turkeys are common, as are deer and coyotes.

Thirty acres is thin enough in any direction to be called mostly edge. You can’t walk very far into 30 acres before you come to the other side. Edges have impact. They change animal behavior. That impact here pretty much extends far enough into this woods that little of it is untouched.

Five homesites, an access road, and driveways cut the woods into smaller pieces. The entire fragmented piece is habitat dominated by edge. All of it is changed.

Edges create negative impacts, according to a study in New York state. An increase in edge space brings decreased nesting near trails, alters bird species composition near trails, and increases nest predation by cowbirds, skunks, raccoons and foxes using the clearings, trails and roads for access.

The study also showed that some species of animals are reluctant to cross openings, even to fly across openings. This reduces land available for nesting territory and foraging.

On the other hand, some species find edges attractive. There is more light. Vegetation types change.

Pluses and minuses.

Overall, though, with this change we lose more of a habitat type that is disappearing.

A recent article in the New Yorker addressed the environmental impact of roads (“What Roads Have Wrought” by Michelle Nijhuis).

She quotes Prof. William Laurance of James University in Cook, Australia, as saying: “Roads scare the hell out of ecologists. You can’t be in my line of business and not be struck by their transformative power.”

Nijhuis writes: “No matter the ecosystem — forest, prairie, patch of moss — the effects of habitat fragmentation are ruinous.”

So, this undeveloped acreage, an almost unknown bonus in a suburban neighborhood like ours, changes. Not an unusual change, just another, one more. We also see new neighborhoods sprouting near here as farmland in once rural townships is cut to pieces for homes.

We’ll learn to live with it. The learning curve for animals is called evolution.


Read Jim Williams’ birding blog at startribune.com/wingnut.