Wolves howl when they are separated from a close companion or a high-ranking pack member, according to a new study published in the journal Current Biology.
The finding, those behind it argue, offers new insight into just how voluntary and meaningful animal vocal production can be -- a question research has offered very few answers for over the years.
"Our results suggest the social relationship can explain more of the variation we see in howling behavior than the emotional state of the wolf," says Friederike Range of the Messerli Research Institute at the University of Veterinary Medicine Vienna. "This suggests that wolves, to a certain extent, may be able to use their vocalizations in a flexible way."
The experiment came about after handlers at the Wolf Science Center found that every time a wolf was taken out for a walk, its remaining pack mates would begin to howl.
To discover the reason behind this, Range and colleagues measured the wolves' stress hormone levels during these occasions, in addition to collecting information on each wolves' status within the pack and their preferred partners. Finally, they recorded the wolves' reactions as their peers were separated from them.
In doing so, the researchers discovered that wolves howl more when a pack mate they have exhibited close affiliation with or that boasts high social rank is removed. However, the amount of howling did not correspond to higher levels of the stress hormone cortisol, the scientists determined.
Based on these results, Range said the study suggests "that howling is not a simple stress response to being separated from close associates but instead may be used more flexibly to maintain contact and perhaps to aid in reuniting with allies."