Hunters and Hunted
Mammals’ intelligence allows them to learn from past experience and develop novel solutions to problems. Nowhere is this more apparent than in the life and death struggles between the hunters and hunted.
Cheetahs are solitary hunters with a fragile build. This limits the size of prey they can bring down. However, in the perfect demonstration of mammalian intelligence, cheetahs in northern Kenya have broken free of these limitations.
Uniquely, three cheetah brothers not only live together to defend their territory, they have also learned to hunt together, as lions do. They alone, of all cheetahs, can tackle big prey like ostriches. Mammals can pass new skills to the next generation, but since male cheetahs play no part in the raising of their young, the brothers’ novel hunting method will probably die with them.
Family bonds are essential if novel skills are to be passed on. A pod of nine killer whales live off the Falkland Islands. One female alone has discovered a way to edge into a tidal pool where, for a few weeks each year, elephant seal pups learn to swim. With great stealth she can grab a naive pup, saving herself the trouble of catching seals in the open sea. This skill may not be lost since her calf is learning the technique by following her.
When skills are passed on a whole local population can become experts. Dolphins in Florida Bay work as a team to corral fish. The lead dolphin swims in a circle round a shoal of fish, beating its tail on the sea bed to create a ring of mud. The panicking fish try to leap out – straight into the mouths of the waiting dolphins.
The skills mammals develop to outwit prey can be intricate and surprising. Scientists recently discovered that the star-nosed mole in Canada smells its prey underwater by exhaling a bubble from its nostrils and then re-inhaling it ten times a second.
Most predatory bats use echolocation to sense their prey, which they snatch from the air. But greater bulldog bats sense ripples on water made by swimming fish. They skim close by and use their enlarged feet as grappling irons to pluck the fish into the air.
But skill learning is not restricted to hunters. The hunted can develop novel ways to outwit the hunters. In the forest of Bandhavgarh in India chital deer live under constant threat from tigers, which are hard to spot through the grass and trees. So the deer have learned to listen to langur monkeys in the trees. From the monkeys’ elevated position they spot approaching tigers and make alarm calls, giving the deer an early warning to escape.