A coastal mangrove forest was cleared and transformed by humans into shrimp farms. The destruction of the original habitat poses a serious threat to the local population of capybaras, which are large rodents. Environmentalists initially predicted that the capybaras in the area would disappear within three years. After one year, the population of capybaras is already reduced by one-third, but it is unlikely that they will completely disappear from the region within the next two years, since _______________.