What humans have done to the environment (1)

I often come across snails, snakes, slugs, earthworms, caterpillars or other slow-moving animals on paved roads. They are trying desparately to "run back" to safety , but their speed is not fast enough so they won't get hit by cars, or even by bicycles. While there are a number of more serious environmental problems, our daily ordinary & convenient lifestyles are also posing threats to many living things --they are often unnoticed.