severe impacts on the tree snail fauna of Hawaii and other Pacific islands. The black rat "Rattus rattus" appears to be a major threat to the Newcomb's tree snail on Maui. During the first year of the mark-recapture study initiated in 1996 for Newcomb's tree snails, evidence of rat predation on other tree snail species within the study area was documented. No direct evidence of rat predation on Newcomb's tree snails were found, though researchers theorized that no Newcomb's tree snail shells were found because of their fragility, small size, and brown coloration, which would make it much more difficult to find in the leaf litter in comparison to other predated snail shells. Norway rat "Rattus norvegicus" and Polynesian rat "Rattus exulans" are the major introduced predators on extant populations of Hawaiian tree snails.