Context . Livestock guardian dogs (LGDs, Canis familiaris) can be highly effective in protecting livestock from predators; however, how they accomplish this, is poorly understood. Whereas it is clear that these dogs spend a high proportion of their time accompanying livestock, and confront predators that approach closely, it is unknown whether they also maintain territories around the areas used by their livestock and exclude predators from those territories.

Aims . We aimed to determine whether LGD behaviour towards predators is consistent with defence of a larger territory that encompasses the stock, or is based on repelling predators that closely approach livestock.

Methods . We used audio playbacks and scent placements to simulate incursions by dingoes (Canis dingo) at different locations with the LGD ranges, and used GPS tracking and automatic cameras to monitor responses to these incursions.

Key results . The LGD responses depended on location of the incursion. When simulated incursions were a significant distance inside the range (about the 50th kernel isopleth), they responded by vocalising, leaving their livestock, and travelling up to 570 m away from the stock to approach the incursion point and display challenging behaviour; when incursions were at the boundary of the range (at or beyond the 90th kernel isopleth), they vocalised but did not approach the incursion point, regardless of the location of the sheep. The LGDs in this study worked in groups. Group members responded differently to simulated incursions, some moving to challenge, whereas others remained close to the sheep.

Conclusions . Our results showed that protection by LGDs extends beyond the immediate vicinity of livestock, and is consistent with the defence of a larger territory.

Implications . If predators are excluded from this territory, LGDs enforce a spatial separation of predators and livestock. This would reduce risk of attack, but also prevents the disturbance and stress to livestock that would be caused by frequent approaches of predators. Where possible, training and management of LGDs should allow them to range freely over large areas so that they can develop and exhibit territorial behaviour, and they should be deployed in groups so that group members can assume complementary roles.