Habitat destruction, especially of the humid forests in the tropics, is the main cause of the species extinctions happening now. New work documents the uneven, highly clumped distribution of vulnerable species on the Earth, and pinpoints 25 so-called ‘biodiversity hotspots’. Seventeen of them are tropical forest areas, and here reduction of natural habitat is disproportionately high. Nonetheless, identification of this pattern should enable resources for conservation to be better focused.