The wealth of data generated from intensive study of the brown tree snake as a result of the need to control introduced populations of this pest species allow several important conclusions. First, that the snakes on Guam are extraordinary in terms of their absolute abundance and in terms of their ability to exploit a broad prey base. Our data suggest an exceptionally high reproductive success on Guam for a snake with an otherwise unnoteworthy reproductive capability and life history (i.e. small clutch size, typical ontogenetic shift from small heterothermic prey to larger homeotherms). Especially important was the snakes versatility in taking advantage of extremely common prey on islands; population expansion was slow but survival was maximal, ultimately leading to high population levels. The brown tree snake shares many attributes with other snakes that could cause similar biodiversity crises in a wide variety of contexts in which they lack coevolutionary histories (especially formerly snake-free island environments). As opposed to their relatively poor history as over-water dispersers, snakes may be especially problematic as travelers in increasing ship and air traffic between widely separated geographic regions of the world.