Every year cars, vans, and trucks traveling on America's public roads kill millions of animals. Highway construction, like urban and residential development, often destroys or fragments their habitat. Critter Crossings: Linking Habitats and Reducing Roadkill highlights some successful overpasses, underpasses, and resource management approaches that are helping to meet this challenge.
On these Keeping It Simple pages you'll read about numerous "easy," complementary strategies that help make roads more wildlife friendly. You'll also read about simple ways states are managing roadside habitats...minimizing highway construction's impact on sensitive species...controlling highway runoff so it doesn't pollute water and harm aquatic life...and improving roadside lighting so it doesn't disrupt the flight pattern of migratory birds.
Low bridge rails can put some bird species at risk of flying into traffic, and bright lights on bridges can slow the passage of some fish species. Clay, sand, and other sediment suspended in water during bridge construction can also kill aquatic organisms or degrade important aquatic habitat. The runoff from bridges caused by traffic and maintenance activities can adversely affect aquatic organisms, too, when pollutants enter the water in sufficient concentrations to do harm. And some wildlife species are sensitive to disturbance resulting from bridge and road construction work in their vicinity.
Here are some things state transportation agencies have done to prevent these problems from occurring:
Highways and bridges take us over scenic bays and rivers and across picturesque lakes and streams. Yet the wildlife and fish sometimes pay a price for our enjoyment of these natural waterways. Highway, bridge, and culvert construction can cause severe impacts to stream habitats - especially when the stream channel has to be relocated. Sediment from construction activities can cloud the waters of a stream, making it harder for fish to find food and occasionally covering fish eggs or mussel beds. De-stabilizing stream banks and removing streambank vegetation can destroy wildlife habitat and eliminate shade-cover for fish and aquatic insects (food for fish, birds, and bats). Improper culvert design can also affect how freely fish can move up and down the stream corridor to successfully carry out their life cycles.
The examples that follow highlight some simple methods state transportation agencies and Western Federal Lands are using to counter the effects of stream relocation and to correct barriers to fish passage. The examples also illustrate the easy things these organizations are doing just to enhance wildlife and fish habitats along waterways. The efforts they're making do more than help protect habitats - they help protect the entire food chain.
Wetlands and adjoining uplands provide habitat for about one third of all federally endangered and threatened plant and animal species and nesting spots for more than half of the country's birds. Since colonial times, these valuable wetlands have been disappearing. Twenty-two states have lost at least half of their original wetlands; several states have lost more than 90 percent of their wetlands. Reversing the trend of disappearing wetlands and enhancing the values and functions of new and existing wetlands involves "complex" solutions like wetland mitigation banking and tailoring clean-water strategies to specific watershed conditions. Reversing the trend also has a lot to do with applying "simple" strategies that protect, enhance, or even create wetlands. In the examples highlighted below, you'll read about simple efforts ranging from building a nesting box to creating bird perches and small-animal habitats to avoiding practices that interfere with "natural" vegetation growth.