Nor, for that matter, do zebra mussels, crazy ants or Nile perch. When alien species invade, they wreak havoc on economies and ecosystems across the globe. Curbing the problem is an international task, says Harold A. Mooney, a Stanford biologist who helped design a global plan to deal with the invaders. If we have a fire, then we send for the fire truck.
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Behind habitat destruction, alien invasion is the second greatest cause of species extinction worldwide. Today, only one bat species remains, three forest birds and six native lizard species. Biodiversity loss, though devastating, is not the only issue. More than one million nocturnal brown snakes now inhabit even the smallest spaces on Guam. They cause blackouts by crawling on power lines, hunt in family chicken coops and slide into homes through bathroom vents.