Robin McKie reviews The Sixth Extinction: An Unnatural History by Elizabeth Kolbert: Brown tree snakes come from Papua New Guinea and Australia, where they survive on diets of lizards, bats and rats. They were considered unremarkable until the 1940s when some found their way to Guam, probably on a military ship.
The impact of Boiga irregularis was staggering. The little Pacific island’s only indigenous snake was a sightless creature the size of a worm. As a result, Guam’s fauna were unprepared for the predatory brown tree snake that began to eat its way through the island’s native birds, including the Guam flycatcher and the Mariana fruit-dove, as well as its three native mammals, all bats. Only one of the latter survives: the Marianas flying fox, which is now considered highly endangered.
It is a sad, familiar story. In colonising our planet’s nooks and crannies, most new species that we have encountered have either been wiped out directly – like the mastodons, mammoths and Neanderthals laid low by our stone age ancestors – or indirectly by the pests we introduced in our wake, like the brown tree snake or the Central American wolfsnail, introduced to Hawaii in the 1950s, which has since killed off around 90% of the islands’ 700 native snail species.
Then there are the coral reefs, homes to vast numbers of marine animals, that have been dynamited by fishermen and bleached by our acidifying oceans. Or consider the swaths of the Amazon basin ploughed up for farming, thus destroying the homes of countless rainforest denizens. And for good measure, there are the fungal diseases, spread by humans, that now threaten every bat species in America and every amphibian species on the planet. When it comes to sharing a planet, we are the neighbours from hell.
“One-third of all reef-building corals, a third of all fresh-water molluscs, a third of sharks and rays, a quarter of all mammals, a fifth of all reptiles, and a sixth of all birds are headed toward oblivion,” states Elizabeth Kolbert in this compelling account of human-inspired devastation. “And the losses are occurring all over: in the South Pacific, in the North Atlantic, in the Arctic and in the Sahel, in lakes and on islands, on mountaintops and in valleys.” [Continue reading…]