Of all the strange, and unfortunately rare, animals that live in the forests of Madagascar, the aye-aye must surely be the strangest. Many of these rare animals are lemurs, to which the aye-aye is closely related. The size of a cat, with a bushy tail as long as its body, the aye-aye has a coat of thick, dark brown or black hair. The face is rounded, with large eyes and naked ears, erect, rather like those of a mouse.
The fur around the face and throat is yellowish-white. The aye-aye could be described as almost squirrel-like, except for the bizarre hands and feet. Like those of other primates (lemurs, monkeys, apes) the hands and feet have opposable thumbs. Those of the hind feet have flat nails but all the other toes have pointed claws. The middle finger of each hand is extremely long and narrow, and is used for feeding and for combing the fur, for scratching and for picking the teeth.
Aye-ayes live only in northwestern and eastern Madagascar where they inhabit forests, mangroves and bamboo thickets. Occasionally they are found in cultivated areas such as coconut plantations, but it is largely the clearing of the country for agriculture that has caused the aye-aye to become very rare. Where they have adapted themselves to life near human settlements they appear to be little disturbed by the general activity, motor transport, transistor radios and so on.
Man and the aye-aye rarely meet, as the aye-ayes are nocturnal, spending the day in a hollow tree or among branches. The Malagasy regard it with dread, as a mere touch from it is supposed to cause death. When irritated by man it is fearless, lashing out with its long, clawed fingers. Another legend credits aye-ayes as the reincarnated ancestors of the Malagasy.
Aye-ayes are mainly silent creatures, but they occasionally emit a short cry rather like pieces of metal being rubbed together.
Listening for food
Fruit, insect grubs, and possibly adult insects make up the aye-aye’s diet. The two peculiar structures in their anatomy, the long middle finger and the rodent-like front teeth, are used for getting food. After nightfall an aye-aye creeps around the branches listening very carefully for the sound of an insect grub chewing its way through the wood. If it cannot hear anything, it delicately taps the branch with its long middle finger, listening, with all the skill of a piano tuner, for the change in sound that indicates a hollow where, perhaps, a grub is lurking. If an opening to the hollow can be found, the aye-aye will insert its long finger and try to hook the grub with its claw and haul it out. Failing this, the chisel-like front teeth are used to gnaw away the wood until the prey can be reached.
The front teeth are also used to pare away the hard wood of bamboos to get at the soft pith. Recently a French zoologist has described a pair of aye-ayes living in a coconut plantation. The ground was liberally scattered with half-eaten and abandoned coconuts. The aye-ayes came out in the evening and walked around the trees, each selecting a suitable nut. The incisors were used to sink a hole an inch or so in diameter into the side of the nut; then the middle finger was used to extract the milk and pulp, by poking it in the hole then licking off the adhering mush. Aye-ayes use the same trick for drinking water, sweeping it to the mouth at about 40 strokes a minute.
The single young is born in a spherical nest about 20 in. in diameter with an opening in one side. It is built in a hollow tree or in the crotch of a branch. Apparently, the young are born in February and March. Nothing is known about mating, gestation period or whether the father stays with his family.
In 1933, the aye-aye was thought to be extinct, but it was rediscovered in 1957 by Professor J. J. Petter. However, by 1966, it was considered that less than a dozen aye-ayes were left. Then the island of Nosy Mangabé, just off Madagascar, was declared a reserve and nine aye-ayes were transferred to it. But, by 1976, there seemed to be only two or three left.
An animal out on a limb
An important guide for the classification of mammals into their natural groups is the form of their teeth. For instance, the insectivores have sharp-pointed teeth suitable for crushing hard-bodied insects and the rodents have chisel-like front teeth suitable for gnawing. So when the aye-aye was discovered by a French explorer in 1780 he informed the scientific world that he had found a new species of squirrel (that is, a rodent). This was, in many ways, excusable. The aye-aye has long, chisel-like gnawing teeth (incisors) which, in true rodent fashion, grow continuously; there are no piercing (canine) teeth and the cheek teeth (molars) are flattened for chewing. It was not until its anatomy was fully studied that it was seen to be a primate. The opposable thumbs, the flat nail on the big toe, as well as a few characters of the skull, showed that it was definitely a primate, a relative of lemurs and monkeys. Even so it was a strange primate, having no really close relatives, even among the lemurs. Some of its features are very like those of extinct primates, so the aye-aye is the remaining, and now very withered, branch of a very old stock. In an evolutionary sense, no less than in its nightly wanderings, it is an animal out on a limb!