Creeping Impacts

In a Nutshell: Habitat can be so severely degraded that some wildlife will no longer use it simply because of our presence and the activities that we consider normal. In a forest, add one house, one family, one dog and one cat along with the lights and hammering, and animals will vacate.

Discussion of our impacts on the environment often seems to suggest that the only important impacts are big, severe and obvious. Don’t believe it. Environmental impact statements sometimes have trouble dealing with them but many of our impacts these days creep up on things rather than blasting them out of their habitats.

What has been the creeping effect of our introduction of snowmobiles and ATVs into previously quiet stretches of bush? Push it up one step. What have highways done over time to the environments along them? Not only do they turn wildlife into roadkill, but the effects of highways and motorized trails extend well beyond a narrow traveled line. Vegetation, with or without leaves, does not stop much noise. It takes solid, flat things like the noise barriers along superhighways. A multi-year study in The Netherlands showed that highway noise reduced the successful nesting of several bird species for up to 200 metres on each side of the road. The Dutch government has now dug some of their new roads down into giant trenches so that the side walls catch some of the noise and better protect the environment beyond.

We create many creeping impacts that are hard to notice. I live on a small peninsula that is hard to get onto for many kinds of wildlife. We have built our houses along both edges of the peninsula and our road down the middle. Foxes that used to have pups on our bush lot only visit now. Without considering how activities around homes restrict the movement of some species, our impacts crept through most of the habitat. Some wildlife can no longer live with us. Dogs, cats, humans, smoke, noise, light, all can do it, depending on the sensitivity of the wildlife.

If we plan a housing development, how many dogs does that mean? How much noise? How much excess light going into the night forest? Dogs from homes built near the woods can put an end to nearby deeryards. But cats, both yours and the ones dropped off along the road, can be an even greater impact creeping out from our houses into the surrounding habitats. Good, multiyear studies have shown that not only do cats reduce the numbers of many kinds of wildlife but they also can completely exterminate some species locally. Cat owners should know that coyotes prefer cats as prey so it would be better for the cats as well as the environment around the house if the cats were kept in the house or in an outdoor cat kennel. It may be cruel but fortunate that coyotes like to eat cats.

Species vary in their sensitivity to our creeping impacts. Some species have learned to live with humans and even to use resources that we supply, such as our garbage. As our impacts creep up on them, we chase away sensitive species and soon the only species that we can see and experience close to home are “weedy” ones like raccoons, gray squirrels, crows and, eventually, in cities, just Norway rats, raccoons, starlings and pigeons.

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