Abundance and Diets of Rats in Two Native Hawaiian Forests

Abstract

Snap traps were set and monitored in two native Hawaiian rain forests on Maui, Hawai'i, to determine the relative abundances, distributions, and diets of rodents. Black rats (R. rattus), Polynesian rats (R. exulans), and mice (Mus musculus) were abundant throughout the mesic to wet forest habitat in both areas from 1600 to 2000 m elevation during both summer and winter trapping periods. Invertebrates, particularly insect larvae, were the most frequently found and abundant food item in the stomachs of both rat species. Consumption of these prey by rats was higher in winter than in summer. Black rats ate more fruits, seeds, and other vegetation than did Polynesian rats. More information about the life history, ecology, and behavior of rats in native Hawaiian forests is needed to document their impact on endemic ecosystems and to develop effective control techniques.