Why Do Rabbits Have Large Ears?
A rabbit’s ears help in monitoring environment and detect predators. Rabbits can pick up sounds over considerable distances, perhaps up to 3km. Their ears can be rotated 270 degrees to help detect the source of a sound, and can revolve independently to monitor different noises.
Rabbits are timid animals with many enemies and rely on their large ears to warn them of the sound of approaching danger. Their ears act like old-fashioned ear-trumpets. The large area catches a great many sound waves and channels them into the rabbit’s inner ear. However not all rabbits have big ears – some domesticated breeds like the Netherland Dwarf have short ones.
Wild rabbits spend most of the day underground, usually coming out to feed between dusk and dawn. They are continually on the alert, their long ears twitching and moving round to pick up the faintest sound from an enemy.
They also have a keen sense of smell. Long back legs give rabbits speed. But they are virtually defenseless and, in fact, often seem to be hypnotized by approaching predators.
When this happens, they crouch squealing and make no attempt to run away. Only their extraordinary fertility has enabled them to survive the onslaughts of foxes, badgers, wild cats, martens, stoats, weasels, polecats, dogs, man and disease.
Secondly, they assist in thermoregulation. A rabbit’s ears contain an extensive network of blood vessels that provide a large surface area for heat exchange. These vessels swell (vasodilation) when the rabbit is hot, and contract (vasoconstriction) when it is cool, so much so that they are barely visible in cold weather.
Rabbits are native to Spain and southern France, but have been introduced to many other parts of the world. Though they differ in size across the globe (those in Australia and Britain are 50 per cent larger than those in Spain), ear length is relative not to body proportions but to climate: in Britain they are 60–70mm long, in Spain about 75mm long, and in the arid parts of Australia roughly 80mm long, to help the animals cope with the hotter conditions.