“When alien archaeologists exhume the rubble of human civilisation,” says Ben Goldfarb in Smithsonian Magazine, “they may conclude that our raison d’être was building roads.” There are some 40 million miles of them encircling our planet, from the “continent-spanning” Pan-American Highway to the labyrinth of illegal logging routes in the Amazon. But while roads represent “connection and escape” to humans, to animals they spell “death and division”. They cause more vertebrate deaths on land than any environmental ill – dams, poaching, megafires. “More birds die on American roads every week than were slain by the Deepwater Horizon oil spill.” And it’s getting worse. Fifty years ago, just 3% of land-based mammals died on roads; by 2017, it was 12%. “It has never been more dangerous to set paw, hoof or scaly belly on the highway.”
Yet roads “select winners as well as losers”. The rainwater that drains off Arizona’s highways softens the desert soil for pocket gophers, whose tunnels parallel the routes “like subway lines”. Butterflies whose prairies have been replaced by cornfields “find succour in unkempt strips of roadside milkweed”. And we humans are slowly getting better at mitigating their effect, with what’s known as “road ecology”. We build “bridges for bears, tunnels for turtles, rope webs that allow howler monkeys to swing over highways”. In Kenya, elephants wander under roads and railroads “via passages as tall as two-storey houses”. We’ll always need roads, because, as the Charlotte’s Web author EB White put it, “everything in life is somewhere else”. But hopefully we can at least reduce how much damage we cause getting there.