May 11, 2007 —A small fawn, startled by an approaching coyote, calls out in distress. From valleys as far as 1,640 feet away, vigilant deer mothers — some not even from the fawn's own species — run to the rescue, standing guard and risking their own lives until the predator leaves.
New research on this fearless behavior shows that while all does run to the rescue of their own young, mule deer moms will go to great lengths to save their own young and that of at least one other deer species, the whitetail.
"Mule deer females confront coyotes, and defend fawns and even other adults throughout the year," wrote lead author Susan Lingle, a researcher in the Department of Psychology at the University of Lethbridge in Canada.
Lingle and her team observed deer interacting with predators on a large cattle ranch in southern Alberta.
At first they noticed that female mule deer cooperated to form nurseries in which they raised their fawns. Juveniles may stray, however, or the females may have to leave the nursery for food, drink or other reasons. If a predator, usually a coyote, approaches, the mother mule deer jump into action.
The deer mothers' single-minded instinct to save juveniles appears to drive the behavior, at least in part. But aside from that, the researchers wondered if other factors also played a role.
The scientists played fawn distress calls to both mule and whitetail deer moms. While the latter only responded to calls made by their own offspring, the mule deer made no such distinctions.
The mule deer females usually identified their young by a combination of scent, sight and sound. Since scent only works at close distances, mothers at a distance from fawns sometimes have to rely on sight or sound alone — which could mean they don't always get it right.
