Communication between wolf and domestic dog revealed from experimental scent marking

The European grey wolf (Canis lupus) and the domestic dog (Canis lupus familiaris) share not only a common origin but also many similarities in their behavior. Due to the implementation of protection wolves repopulated large parts of Europe. The increase of wolves in human-dominated landscapes also leads to a growing potential for interactions between wolves and domestic dogs. However, these interactions between wolves and dogs are still poorly understood. Scent marking is one of the main forms of communication in canids, as is crucial for territorial marking, synchronization of reproduction, establishment of hierarchies in groups, and formation of new breeding pairs. We hypothesized that the presence of scent markings by domestic dogs in wolf territories elicits a behavioral response of wolves and therefore may interfere with natural wolf behavior. To test this, we experimentally scent-marked objects within known wolf home-ranges in the Kampinos National Park (Poland) to simulate the presence of "unknown dogs" (dog urine from outside the area) and water as a control. To test whether and how the behavioral response differs between domestic dogs and wolves we additionally created scent marks of "unknown wolves" (wolf urine from outside the area). By means of camera traps we studied the behavioral repones of local wolf families exposed simultaneously to all three scent stimuli. Our study showed that wolves (breeding pair) reacted to scent marking from "unknown dog" in 16% of cases, while an average juvenile reacted in 27% of cases. In 33% of cases, the breeding pair overmarked stimuli from an "unknown dog" and in 27% of cases mark them by ground scratching. Wolves spend significantly more time exploring and sniffing scent marks of "unknown wolves" than "unknown dogs". Our result indicates that domestic dog scent marks trigger a behavioral response in wild wolves showing that it does affect their behavior. The longer time that wolves spend on responding to wolf scent marks compared to dog scent marks indicates they can distinguish between wolf and dog scent marks, but especially inexperienced juveniles spend much time exploring dog scent marks. This suggests that the increasing occurrence of dogs inside wolf territories could affect and potentially disturb the scent-marking behavior of wolves.