Dispersal movements by wild dogs in eastern Victoria, Australia
Wild dog fitted with a GPS collar. Image - Alan Robley.
Wild dogs (dingoes, feral dogs and their hybrids) are an important apex predator throughout Australia. However, they also cause economic and social distress to farming communities because they injure and kill livestock, causing an estimated A$48.5 million in damage annually. To reduce the incidence of attacks on livestock, wild dogs are controlled (usually with buried toxic baits) on land adjacent to areas with livestock, with baiting concentrated within 3 km of pastoral land.
Several studies have investigated wild dog movements in temperate and semiarid land. However, little is known about their movements around heavily forested environs of south-eastern Australia. Andrew Gormley and Alan Robley used collars fitted with GPS receivers to investigate the movements and habitat use of wild dogs on Nunniong Plain in eastern Victoria, in an area that contains sheep and cattle grazing areas adjacent to public land. Nine wild dogs were captured and had collars fitted, with the GPS devices programmed to gather location information every 30 minutes for 3 months, then every 8 hours for the next 6 months, at which time the collar was set to automatically fall off. The aim of the project was to investigate patterns of wild dog movement and habitat selection at the home range scale, and to see whether features with suspected high relative use (e.g. roads and watercourses) could be identified in order to better target wild dog control operations.
Home ranges varied among individuals from 30 to over 200 km2, with males (124 km2) having larger home ranges on average than females (45 km2). Most collared individuals had overlapping home ranges, suggesting that they were part of a social pack.
Wild dogs displayed a high degree of memory of their home range, with individuals recorded as traversing their entire home range within days, often returning to a small number of ‘high-use’ locations where they would remain for a few days.
Two of the dogs, however, had unexpected long-range-dispersal movements during winter. One male travelled north for 60 km over 3 days towards the Victoria–New South Wales border, before returning to its home range on Nunniong Plain. After a further 30 days, he again headed north, this time travelling 230 km over 9 days, before again returning to his home range, stopping for a week at an intermediate location (Long Plain) along the way. Finally he again headed north, this time to Long Plain, where he remained for 3 weeks, at which point the collar fell off.
Similarly, a female left her territory in June and travelled north for 20 km over 6 days, spending a week at the new location, and then returned to her home range. A second long-range movement then occurred, which saw her travel 105 km over the next 3 months.
These two long-distance movements are unlikely to be associated with a move to lower country in winter, as all the other dogs remained on Nunninong Plain despite significant snowfall. Instead, Andrew and Alan believed that these recorded movements are initial forays into new environments followed by permanent dispersal. This type of dispersal behaviour has been previously reported in wild dogs in other land-types and is often associated with high population density and lower food availability.
The two recorded long-range movements were generally within public land reserves. However, they crossed areas that had both currently and previously been baited to control wild dogs. The fact that wild dogs are capable of moving across much larger distances than a single 100-km2 territory may limit the effectiveness of some control frameworks (i.e. control concentrated within 3 km from the farm boundary). To better protect livestock, managers need to know how often dogs disperse across multiple territories before settling, and more specifically how often these movements take them onto private land.
This work was funded by the Department of Primary Industries, Victoria.