Today’s Factismal: Every day, more than a million animals (not counting insects) are killed on US roads.
Loudon Wainwright had it right when he penned the infamously funny Dead Skunk In the Middle of the Road; there are dead skunks, cats, dogs, frogs, raccoons, and a variety of other critters along the road. Known as roadkill, these animals represent both the perils of progress and a unique research opportunity.
Roadkill is as old as roads. Roman chariots ran over rabbits during the time of Caesar, just as modern automobiles do today. But there are many more chariots driving on more roads than ever before. As a result, more than a million vertebrate animals are killed every day by automobiles in the USA alone, along with an additional 200 people each year. And, in some cases, roadkill begets roadkill as scavengers such as vultures and foxes that have come to feast on the dead animals become victims themselves.
But roadkill is also an opportunity for scientific research. At its most basic level, roadkill tells us what types of animals live in an area and gives us an estimate of the relative populations. But the research can also discover interesting new things, such as the study showing that cliff swallows are evolving in response to automobiles.
American cliff swallows are fast little birds that feed on insects and prefer to live on steep-sided cliffs, like those found on automobile underpasses. But living near traffic carries lots of hazards, not the least of which is becoming roadkill. A pair of scientists from the University of Tulsa have studied a collection of roadkilled swallows dating back thirty years, and have discovered something interesting. The swallows that die as roadkill have longer and slower wings than the swallows that are now found nesting underneath the bridges; evolution has selected for a shorter-winged swallow in just thirty years. This has led to a marked decrease in the number of swallows being killed by automobiles even as the swallow population has increased. (Evolution works. Who knew?)
Theirs isn’t the only roadkill study, and it won’t be the last time that something interesting is seen. If you’d like to join in on the fun, then why not join a roadkill citizen science project?