If watching Bambi didn’t convince you that deer are the most loving and caring mothers of the animal kingdom, then this new study definitely will.
According to researchers, female mule and white-tailed deer will respond to the cries of babies outside of their species—including domestic cats and dogs, sea lions, and human babies—if the distress calls fall within the same frequency of young deer.
Researchers Susan Lingle of the University of Winnipeg and Tobias Riede of Midwestern University in Glendale, Arizona, conducted a series of experiments to see how mother deer would react to hearing distress calls of various mammals.
For the experiment, a researcher hid a speaker playing recorded cries approximately 100 to 200 meters upwind from a mother deer. The researcher then hid 25 to 50 meters away, operating an iPod connected by cables to the speaker to control the distress calls. Meanwhile, two more researchers who stationed another 500 to 1,000 meters away watched how the deer reacted through binoculars and high-res spotting scopes. If the deer approached the speaker when she heard the crying, it was considered a positive response.
Upon hearing the calls of young fur seals, marmots, cats and other ungulates, female mule deer would come within 10-meters of the speaker. And upon hearing the calls of sea lions, bats and humans, they would come within 25-meters. White-tailed deer would also approach the speakers after hearing the cries. In some cases, the deer would emit their own contact calls in response as they do when reacting to their own distressed offspring.
When the researchers played the cries of mammals outside of their own fawn’s frequency or the cries of predators, the deer would not approach.
The study concluded, “Our results suggest that acoustic traits of infant distress vocalizations that are essential for a response by caregivers, and a caregiver’s sensitivity to these acoustic traits, may be shared across diverse mammals.”
This would also explain why dogs react so compassionately when they hear their owners sobbing, and how a black bear mother would adopt an abandoned grizzly bear cub as one of her own.