Home ranges and mortality of a roadside Koala Phascolarctos cinereus population at Bonville, New South Wales

Abstract

Vehicles and Koalas Phascolarctos cinereus collide frequently where the Pacific Highway crosses a 3.5 km stretch of forest in Bongil Bongil National Park. Despite the number of road-kills, resident Koalas survive in a 200-500m wide area of forest that lies between the highway and a parallel powerline easement, and seldom cross either boundary. Home ranges of radio-collared animals (which included some overlap) were 22.7 (± 5.1 s.e.) hectares for males and 9.7 (± 1.1 s.e.) hectares for females and extended to the very edge of the highway. Most road deaths, which peaked in September and October, therefore result from young, dispersing animals attempting to cross the highway. Moreover, the locations of fatalities coincide with the intersection of side-tracks and the highway suggesting that some animals are dispersing along the tracks until they meet the highway. Realignment of the highway will reduce habitat for Koalas and is likely to affect some resident animals.After construction of the upgrade is complete,which will include over-and underpasses and associated exclusion fencing to cater for dispersing animals, we predict that Koalas will re-establish home ranges to the edge of the realigned highway.