Seasonal activity and movements of Rattus rattus (Rodentia, Muridae) in a Hawaiian macadamia orchard

We determined activity and movements of Rattus rattus in a Hawaiian macadamia (Macadamia integrifolia) orchard from 3,006 radio locations of 54 individuals during 3 periods of the crop cycle. Most rats remained in burrows during the day, emerged 1-2 hours after sunset, ascended into the canopy, and returned to their burrows 1-2 hours before sunrise. Minimum convex polygon home ranges averaged 0.20 ha (SE = 0.02) and did not vary between sexes (P = 0.17) or among peak anthesis (flowering), midseason, and peak harvest (P = 0.54). Movements as measured by median distance from center of activity averaged 15.4 m (range = 5.6 - 35.7 m) and also did not vary between sexes (P = 0.66) or among periods of the crop cycle (P = 0.10). Only 2 of 51 rats initially captured in the orchard ventured outside the study block. Rats selectively (P = 0.009) utilized variety 660 compared to variety 508 when the former variety had an abundance of mature or nearly mature nuts. Managers should concentrate damage control efforts in the orchard rather than adjacent windbreaks and waste areas, should place rodenticide baits directly in burrows or trees at greater than or equal to 5 locations/ha, and may be able to reduce rodenticide use by selectively baiting in tree varieties that have mature nuts.