Why some wolves react more strongly to trespassers: Breeders may hold key to scent-based barriers Lisa Lock Scientific Editor Robert Egan Senior Editor Wolves use their urine to communicate with each other. A recent study looked at the reactions of a pack to the marking of an intruder. This is a first step toward understanding what attracts or repels canids.

Wolves use their sense of smell—which is far more developed than ours—to hunt or avoid predators, but also to communicate with their fellow wolves. The urine marks that they leave to identify their territory contain information about their identity, rank and reproductive state. Yet this mode of communication, which is fundamental in canids, has received little scientific attention to date.

A study published in Frontiers in Ethology analyzed how packs living in captivity react to the olfactory signal of an intruder. In this controlled experimental setting, Giada Studer, Klaus Zuberbühler and Gwendolyn Wirobski from the Laboratory of Comparative Cognition at the University of Neuchâtel observed much more marked reactions in breeding wolves. In the long term, a better understanding of urinary communication in canids could lead to the development of olfactory barriers against wolves.

Thirteen wolves, five packs, four zoos Between April and June 2024, the team exposed five packs in four Swiss zoos to olfactory stations placed outside along the enclosure peripheries. These stations consisted of an aluminum plate fixed at a height of 30 centimeters (12 inches) from the ground to simulate the natural height of raised-leg urination. The scientists applied 3 milliliters of wolf urine to these plates, protected by a wooden shelter, to mimic the presence of a wolf from outside the pack.

To distinguish a specific reaction from a simple novelty effect, the researchers also used human urine. The reactions of 13 wolves, including six breeders and seven nonbreeders, were recorded continuously by camera traps and analyzed. Breeders more reactive to new scents The result is clear: Compared with subordinate or juvenile individuals, breeding wolves with pups are much more interested in unfamiliar olfactory cues.

"These animals have more to lose," explains Wirobski, a specialist in animal behavior and social cognition in canids, who supervised this study. "They have their territory, their young and their partners. It therefore makes sense that they pay more attention to this social information," she adds.

The behaviors observed were essentially exploratory: approaching, sniffing, urinary or fecal countermarking. Analysis of the reactions showed that wolf urine triggered around 13 times more of these investigatory behaviors than human urine in the breeding animals. They also patrolled almost twice as often as nonbreeders near the scent stations, regardless of the urine applied.

By comparison, nonbreeders showed no significant difference in behavior between the two samples, for the most part doing no more than briefly sniffing them. Complex social communication An individual case provides a striking illustration of the effect of social status. In a pilot test carried out in December 2023, a subordinate nonbreeding female showed no response to another wolf's urine.