A Study of Rattus exulans (Peale) (Rodentia : Muridae) in the New Guinea Highlands

Abstract

A 10-month study of R. exulans in the Eastern Highlands District combined a mark-recapture study on a 1.42-ha grid in grassland with an autopsy study of populations utilizing gardens and houses. The grid study is based on 4-day trapping runs at monthly intervals; the autopsy study on more than 600 specimens. Grassland, garden and house populations differ in basic characteristics (e.g. weights, litter sizes, breeding regimes, injuries, population composition and annual dynamics) with a continuum recognizable from grassland through gardens to houses. Garden and house populations may exist at some hazard; their survival may often require recruitment from grassland areas. For the grid population, spatial segregation by age and sex is apparent, with adults occupying areas of higher and more continuous cover and subadults differentially present in areas of low and often sparse cover. Numerical changes in grassland populations of R. exulans may follow a 3- or 4-y cycle linked to a culturally determined cycle in the domestic pig population. It is suggested thatthe close association between people and pigs may serve to reduce R. exulans populations nearcentres of human habitation and gardens.