Most people have heard squirrels and other animals raise a racket when there’s a predator nearby. Sometimes, the chirps, tweets and screeches don’t change much when a prey species is threatened by a hawk, say, or a prowling jackal. But scientists are becoming increasingly aware of other animals — including prairie dogs, lemurs and red squirrels — that actually distinguish between different types of predators, and their fellows enact different escape strategies in response. Meerkats, social members of the mongoose family that live in southern Africa, are like that.
Roman Furrer and Marta Manser, zoologists from the University of Zurich in Switzerland, thought the meerkat’s communication abilities were curious. For starters, it makes sense when creatures in complex environments use variable sounds to talk about predators, because they can vary the response. This is an unscientific guess: if I were a squirrel and I heard “hawk,” maybe I’d duck under some leaves. If I heard “snake,” I might scamper up a tree. But meerkats live in a way that doesn’t give them many escape options. Pretty much, they can retreat to their burrows. Plus — and sorry y’all, this part’s just plain cute — in some parts of their desert habitat, meerkats live peacefully with Cape ground squirrels, and, the study authors wrote, “often share their sleeping burrows!” [emphasis and exclamation point mine]
The burrow-sharing (besides being positively adorable) is significant because Cape ground squirrels don’t make specific sounds for specific predators. Their communication is much simpler, and varies only in terms of urgency. So the authors wanted to know why two species, which share the same predators, the same habitat and even — sometimes — the same spaces, would use such different strategies to communicate danger.
As it turns out, there are a lot of other differences between meerkats and Cape ground squirrels that could explain it.
First, there’s diet. Cape ground squirrels are vegetarians, feeding on grasses, seeds and leaves that grow pretty close to their burrows. Meerkats, by contrast, eat insects, lizards, small mammals and, rarely, small birds. To get their foods, meerkats have to stray farther from their homes.
And there’s feeding behavior. The authors noted that Cape ground squirrels “often picked up their food items from the ground and fed while squatting on their haunches with their heads pointing horizontally, enabling them to scan their surroundings while feeding.” Meerkats are often looking at the ground or even have their noses stuck under the soil, rooting around for prey.
Cape ground squirrels stay so close to their burrows that they don’t need an elaborate escape plan — or predator-specific communication. Everybody just runs and hides, and it doesn’t take much work to re-emerge and feed again once the predator leaves. But meerkats roam farther from the safety of their burrows. Getting caught alone by a marauding predator would be dangerous — and running back home for every threat would burn up a lot of energy. And so, communication is key. Meerkats forage as a group but keep a sentinel on duty, Furrer and Manser wrote. Manser found in previous work that the strategy enables individual group members to let their guards down. And sometimes, based on their communication, the whole group will react less dramatically — and, for example, simply move away from a loitering jackal rather than darting back to the burrow.
The new study is fun because it’s more evidence that animals use advanced communicaton, and because of the cute factor. And it’s scientifically fascinating as another indication that animals adapt to nature in myriad, complex ways.
The new study appears in The American Naturalist, and thanks to Kevin Stacey at Chicago Journals for sending a copy.