Four E’s and a P, Carl Zimmer

Discover, January 31, 1993

Last April a bat-eared alien appeared on the television news. Its name was Blue Devil, and it was the first aye-aye–one of the rarest primates in the world–ever to be born in captivity.

The nocturnal Madagascar native was probably seen by more people than all the other aye-ayes in history combined. Aye-ayes are so hard to track that they have barely been studied, and conservationists are hard-pressed to estimate their total population. It’s just as well that aye-ayes are so elusive: on Madagascar they are often killed by their human neighbors, who consider the bushy-tailed mammals bad luck.

In December 1991, however, primatologist Elwyn Simons of Duke University managed to locate a relative treasure trove of aye-ayes and brought four females back with him to North Carolina. (Researchers at Duke have been organizing a captive-breeding program for aye-ayes, in hopes of restocking Madagascar’s forests.) As the Duke team watched over the next few months, they noted that one of the aye-ayes was gaining weight. That in itself was no reason for undue excitement–weight gain is common among wild animals introduced to a regular diet. Except that this wild animal was actually pregnant.

The birth was discovered on the morning of April 6; Blue Devil–named after Duke’s men’s basketball team–weighed in at five ounces. Since the blessed event, researches have been intently watching mother and child (lighting is artificially controlled so the aye-ayes’ night is the researchers’ day), observing for the first time aye-aye maternal care and infant development.

For his first several weeks Blue Devil just sprawled in his nest inside a box. Gradually, however, he gained enough strength and weight (now about three pounds) to leap from tree to tree. In the wild, aye-ayes act like woodpeckers, gnawing into trees and sticking a long, highly flexible middle finger into the hole to draw out insects. In 1991 Duke psychologist Carl Erickson reported that they detect the insects by tapping this finger on the bark and listening for an echo. Blue Devil, Erickson is happy to report, began tapping and gnawing pieces of wood after three months.

More good news on the aye-aye front took place in the late summer when another aye-aye was born at Britain’s Jersey Wildlife Preservation Trust. Because this mother was bred in captivity, the researchers have learned that the aye-aye gestation period is about 158 days. And on the morning of October 23, Duke was blessed again, when another male, weighing four ounces, was born.

Blue Devil, meanwhile, has quickly learned how to communicate. As infants, all other primates, including humans, make very different noises than their parents do. But Blue Devil has been making adult calls with clear meanings. One, known as a contact call, gets his mother’s attention. “It’s an ‘eeeep! ‘” says Simons. “We spell it with four e‘s and a p.”