Vehicle collisions and visitor disturbance reduce survival and reproductive success of kangaroos in a national park

Abstract

Many protected areas provide opportunities for people to view wildlife using roads and walking trails. The impacts of roads and trails on wildlife populations, however, have seldom been investigated by examining their consequences on individual animals. We studied the impacts of a road and use of a wildlife viewing trail on eastern grey kangaroos (Macropus giganteus) in Wilsons Promontory National Park, Australia. We analyzed 11 years of data from 433 marked individuals to quantify road mortality, and how distance from the road, where the walking trail started, affected survival, movement, and reproductive success. Kangaroos in the west of the study area, nearer the road and around a popular wildlife viewing trail, showed increased mobility, more vehicle-associated mortality, and decreased weaning success and survival, compared to kangaroos in the east that were exposed to substantially fewer visitors. Mature males, the sex-age class most likely to be killed by vehicles, had a 51 % higher probability of road mortality at the western than at the eastern end, contributing to a 47 % decrease in overall survival. Prime-aged females at the western end of the study area, where they experienced frequent exposure to visitors, had a 45 % lower probability of weaning a young compared to females in the east of the study area. Managers should consider these undesirable impacts when planning how to encourage people to interact with wildlife in protected areas.