Reviewed by John McFerrin

This is a book about roadkill.  Three hundred pages about roadkill may not sound enticing but it really is an entertaining and informative book.

The subject is road ecology, how the building of roads affects the places where roads are located.  There is one long and interesting chapter about how the placement of roads affects cities and the people and neighborhoods where the road is located.  Other than that, it is all about roadkill.  Roadkill is the result when the built environment of roads comes in contact with the animal world.  It is through roadkill that the result of that contact become apparent.

There are an amazing number of roads in this country and, for that matter, the world.  They range from small (but numerous) logging roads to multilane highways.  Every one of them has an impact on the world through which they run.  The impact becomes most obvious to humans when they see dead animals on the road but the impacts do not stop there.  Bird songs are different close to roads as birds adjust to the noise.  Animal populations lose genetic diversity when roads imprison them on what are effectively islands.  

Roadkill seems an unlikely field of study.  In spite of this, there is much that is known.  Roadkill increases in proportion to traffic but only until traffic reaches a certain point.  At that point, roadkill drops off because—when traffic is above a certain level—animals won’t even try to cross.  The exception is young males who, like adolescents everywhere, will try anything.  Daylight savings time can increase road kill when it moves rush hour to dusk, when many species are most active.  There is data on roadkill among Giant Anteaters in Brazil and Howler Monkeys in Southeast Asia.  

The book is not just a catalogue of roadkill around the world.  It is a book of solutions as well.  The primary solution is crossings, either bridges over roads or tunnels underneath them.  With the discussions of crossings are discussions of the problems—technical, financial, and political—of installing crossings.  Animals whose defensive strategy is to run from danger will not use a tunnel.  Being confined that way is anathema to their carefully evolved survival strategy.  They have to have a bridge, where they can constantly survey the horizon for danger.  Most animals will not enter a tunnel unless there is visible light from the other end.  For Howler Monkeys neither bridges nor tunnels will work.  They need a system of ropes to cross the gap in the canopy.  

The politics of roadkill are just what one might expect:  money for roads is always contentious.  There is always a question of whether money goes for pavement or animal bridges is ever present.

The economics of roadkill can be quantified.  It is known how much property damage results from collisions with animals.  With this knowledge, it is possible to calculate how long it would take for the cost of damage avoided to pay for an animal bridge or tunnel.  Performing such calculations reveals that the damage avoided usually equals the cost of a bridge or tunnel in a surprisingly short time.

In addition to all the facts and insights into how road affect the natural world, the book offers a change in perspective.  The customary way of thinking of roads is that they are a human convenience, built for the benefit of humans.  The needs of animals are secondary, if they are thought of at all.  

This book offers a more balanced view.  Roads are an intrusion into space occupied by animals.  Humans, and their roads, are sharing the space with the animals who already live there.  It is not that animals are crossing our road but that our road is crossing their forest.  As fellow occupants of the space, it is only fair that the interests of the animals be taken into account.  Considered this way, the question of whether we should build bridges for deer or tunnels for toads becomes obvious.  Why wouldn’t we do that?