Imagine: You’re walking through an alley downtown in the middle of the night. Suddenly, someone behind you in the dark says “Hey you!”
What do you do? Do you run? Hide? Turn around and growl “What do you want?!?” in your toughest voice?
Well, you might say it depends…what did this voice sound like? Was it gruff and menacing or meek and pleading?
If you are an Asian elephant and the “Hey you!” comes from a stalking tiger looking at your calf as a midnight snack, you are going to high-tail it out of there. Turns out elephants react differently to predators based on perceived threat, just as you might react differently when encountering a hobo versus a gangster in an alley at night.
For wild Asian elephants around Bandipur Tiger Reserve and Wayanad Sanctuary in southern India, the alley is a crop field of munchies, the hobo is a leopard who never quite liked the taste of elephant meat, and the gangster is a tiger who would eat elephant for breakfast, lunch, and dinner, if he could. The reactions mentioned above are called antipredator behaviors which prey species demonstrate when threatened. These behaviors could include aggression, flight, alertness, or vocalizing.
Vivek Thuppil and Richard G. Coss of the Animal Behavior Graduate Group and the Department of Psychology at UC Davis hypothesized that the Asian elephant would exhibit different night-time antipredator behavior when confronted with the growls of the two mighty cats, each of which posed a different degree of threat.
Until now, African elephants with their big ears, which are soooo much cooler than the puny ears of their Asian cousins, have gotten all the attention. Scientists discovered that African elephant matriarchs, after listening to a lion roar, can recognize the sex of the lion and act appropriately (cause male lions are WAY more dangerous than females). Older matriarchs are especially quick to signal retreat and alarm calls after hearing nearby African bees. Moral of the story: listen to your mom, she does know what’s best.
But don’t forget about our small-eared friends in India! Turns out all elephants have the ability to communicate with guttural growls and “may possess a broad, low-frequency acoustical-assessment ability” (3). In other words, they probably can tell if that spine shivering roar came from a cat with stripes or spots.
So how do these skills affect an Asian elephants antipredator behavior? Well that’s what Thuppil and Coss disembarked to discover. They used fancy software called AUDACITY to record tiger and leopard-growl playbacks. Elephants approaching crop fields to raid at night would trigger these playbacks by tripping an infrared beam. After months of waiting at three study sites, the scientists collected the responses of seven instances of elephants encountering the tiger-growl playbacks and eight instances of elephants encountering the leopard-growl playbacks for the first time.
Hold up! It’s pitch black. How did tiny humans observe huge and, ideally, agitated elephants in the wild at night? This is where the experiment gets really fancy! They used compass bearing technology on the speaker and the trigger mechanism to provide the elephants movement angle (plus they relied on old-fashioned tracker skills in the morning). But the movements of the elephants encountering tiger-growl playbacks showed nearly identical movements to those encountering leopard-growl playbacks.
The interesting data surfaced when microphones were equipped to high-definition infrared video cameras! With the cameras they analyzed the behavior and vocalizations of the head honcho, usually a matriarch. The vocalizations were categorized into trumpets, grunts, and growls.
With both feline playbacks, the elephants eventually moved away from the growls, but the immediate behavioral responses differed. With leopard-growl playbacks, elephants were immediately alert and investigative. While checking out the area, the elephants tooted their trumpets and grunted loudly, which translated to English probably means “Back off kitty cat!!” But when the tiger-growls were triggered…silence. The elephants did not investigate or growl, instead, they slunk stealthily into the shadows not to be heard nor seen again.
So when elephants hear the vocalization of predators associated with known threats, antipredator behavior kicks in. How can this help conservation? Well, hives of African bees on fences have deterred elephants in Africa from raiding crops. Maybe tiger-growl playbacks can keep Asian elephants out of crop fields and out of the danger of conflicts with farmers.
Hobo or tiger…we are all animals. Sometimes we bark bigger than we bite and sometimes we shut our mouths and do what mom says. Lucky for us and the elephants, evolution has long been shifting and shaping our antipredator behavior. So next time you hear a growl in a sketchy dark alley, don’t worry, you’ll know what to do!
Thuppil V, Coss RG. (2013) Wild Asian elephants distinguish aggressive tiger and leopard growls according to perceived danger. Biology Letters 9: 20130518.