The howl of wolves has fascinated scientists for decades. It has always been presumed to be a way of maintaining contact with other wolves, but for a long time, it was also thought that wolves howl when they are stressed. Making a noise to attract a return howl from other wolves nearby was believed to be a comfort to the howling wolf. However, a recent study into the howling habits of wolves has discovered something interesting – they merely howl to maintain contact with each other and to pinpoint which members of the pack are the highest ranking.
The study, “Wolf Howling Is Mediated by Relationship Quality Rather Than Underlying Emotional Stress,” was published in the online journal, Current Biology in August 2013. Two of the lead researchers from the study were from the University of Zurich, Switzerland, and the University of Veterinary Medicine, Vienna, Austria.
A Live Science article explains how the study worked. One lone wolf at a time was taken away from the rest of its pack by the researchers. Each wolf was kept away from the others for a period of 45 minutes, while the howling of all the wolves involved was measured. The researchers discovered that most howling occurred when more dominant wolves were taken away from the pack. This seems natural because it was clearly unsettling for less dominant wolves to be without wolves they see as leaders.
What was more surprising is that the howling was also liked to the relationship wolves had with each other. For example, the howling rate of a wolf in the pack was greater when it had a positive relationship with the wolf that was taken away. The positive relationship was judged by the amount of time the wolves spent together grooming and playing. This aspect of wolf howling was found to be more important than the hierarchy aspect.
The study also looked at the stress levels of the wolves when they were separated. Saliva samples were taken from each howling wolf and were tested for cortisol levels. Cortisol is a stress hormone. The results showed that stress levels aren’t strongly linked to howling. As one of the researchers told the BBC:
“What we expected was higher cortisol levels if the wolves were more stressed when 'friends' leave, but what we found is that cortisol doesn't seem to explain the variation in the howling behaviour we see.”
The main reason that the howling of wolves has remained so mysterious for so long is, of course, simply that it is difficult to trace and track a pack of wolves for a substantial amount of time. The current study into a pack of captive wolves has therefore shed a great deal of light on the relationship between wolves, showing that they are far more socially adept than previously thought. Much more research needs to be done before scientists can claim to have a good grasp of wolves’ interaction with one another, but in the meantime, there is growing evidence to suggest that wolves are very intelligent creatures.