The world’s most demonic lemur is also its most endangered. Meet the creature with the ugliest finger on the planet.

Behold: the devilish claws of the aye-aye. (Photo: Wikimedia Commons)

At night, in the forests of Madagascar, a dark specter drifts through the canopy. The creature has black, wiry fur, radar dishes for ears, a witch’s broom for a tail, and enormous, haunting eyeballs that shine blood-red in the beam of a flashlight.

Local legend, though, says it’s the aye-aye’s fingers you need worry about.

On each hand, the aye-aye, which is actually a species of lemur, boasts one extra-long digit that looks like the crooked finger of death itself. Some believe that the aye-aye can curse a person simply by pointing at them. Others believe that the creatures sneak into human homes at night and use their skeletal finger to pick at the hearts of their victims.

The precise threat posed by an aye-aye varies from village to village, but the antidote for it is usually the same.

In the wild, the aye-aye prowls along branches and rotting logs, tapping its digit along the bark and listening with its out-sized ears to the sounds that bounce back.

“I was on a trapping expedition back in the early '90s and someone had told us about the location of an aye-aye nest about a day’s walk from the nearest paved road,” says Charles Welch, a conservation biologist who spent 15 years in Madagascar studying lemurs.

Because aye-ayes are nocturnal and generally pretty difficult to find, Welch and company set out into the forest to follow up on the tip.

“So we were walking along the path and we came across what I recognized to be aye-aye fur in the trail,” he says. Convinced it was evidence that they had come to the right place, Welch eagerly questioned the next group of locals they came across at a small general store. They at once confirmed his suspicions and dashed his hopes.

“The night before, the villagers had come across two aye-ayes by accident,” says Welch, “and as a result of seeing them, they had killed them right there.”

The aye-ayes were beaten to death in the middle of the trail. For no other reason than that they were aye-ayes.

“The aye-aye is the lemur that shouldn’t be,” says Chris Smith, education specialist at the Duke Lemur Center.

“It doesn’t look like a lemur. It doesn’t necessarily act like a lemur, but it ends up being one of the most fascinating primates in Madagascar.”

Located in North Carolina, the Duke Lemur Center is currently home to 14 aye-ayes, but it owns and manages over a dozen more housed in zoos across the United States. All told, the Center accounts for more than half of the captive aye-ayes on Earth.

Smith says the most challenging thing about caring for aye-ayes is meeting their physical and mental demands. The aye-aye has the largest brain-to-body ratio of any lemur. So you can’t just give them a treat. You have to give them a problem to solve.

In the wild, the aye-aye prowls along branches and rotting logs, tapping its digit along the bark and listening with its out-sized ears to the sounds that bounce back. This is what scientists call “percussive foraging,” and it’s similar to how some bats and whales hunt.

Once the aye-aye zeroes in on a potential snack, it excavates a hole in the bark using its long, chisel-like teeth. Smith compares these chompers to those of a beaver's because they never stop growing. The aye-aye’s teeth are so strong that captive animals have been known to chew through concrete walls when they’re bored.

After the teeth have done their work, it’s time for the aye-aye to unfurl its primary weapon—the finger. Equal parts pipe cleaner and fishing pole, the aye-aye’s middle finger is an adaptation without parallel in the animal kingdom.

The middle finger of an aye-aye sits on a ball-and-socket joint, just like the human shoulder. This allows it to swivel in any direction, a full 360 degrees.

The finger slips into the tree trunk and snakes around looking for grubs. If it finds one, a specialized claw on the end of the finger hooks the larva and whisks it away to the aye-aye’s mouth. Slurp, crunch, gulp.

In one area of Madagascar, fady might protect the animals by making locals avoid the creatures out of fear.

Back at the Duke Lemur Center, Smith says they have come up with all sorts of contraptions for the captive aye-ayes to simulate foraging. Peanut-butter-and-plywood sandwiches force the animals to gnaw through wood to get their treat. Blocks of wood with holes drilled in them and then sealed up full of wax worms let the aye-ayes practice their tapping.

“They’re very good at what they do, but they’ve ended up not being the prettiest at what they do,” Smith says.

The aye-aye is considered endangered by the International Union for the Conservation of Nature. We don’t know how many of the animals may be left, but the population is generally assumed to be trending downwards. In the 1930s and '40s, it was actually thought that the animals had gone extinct, so few and far between were sightings of the cryptic creatures.

Even for people who live in or near their habitat, coming across the animals can be rare. Edward Louis, director of conservation genetics at Omaha’s Henry Doorly Zoo and Aquarium, says this elusiveness probably has a lot to do with the aye-aye’s distribution and social habits.

Aye-ayes have extremely large home ranges, sometimes stretching as far as 7,000 acres. They also have the largest distribution of any lemur and exist in nearly every habitat on the island. Conversely, Louis says the animals live at very low population densities. That means they’re easy to miss, even if you know where to look for them.

Louis has been catching and collaring aye-ayes as part of the Madagascar Biodiversity Partnership since 2008, and he says he understands why some people might be spooked by this species of lemur.

“They sort of look like a black hole up in the trees,” he says.

And when you throw in the crazy fur, the fangs, the finger, and eyes like burning embers, well, you get a creature that looks every part the demon—especially if you’re not accustomed to seeing them.

But to fully understand the fear, Louis says you need to understand the concept of fady. Translated loosely as “taboo,” the people of Madagascar have fady for all sorts of objects and actions, and the particular fady may differ from town to town, family to family, or person to person. For instance, among the ethnic group known as the Merina, it is fady to hold a funeral on a Tuesday, and violating the taboo is thought to invite another death. There’s a fady against handing an egg directly from person to person, and another that forbids singing while you eat.

“One village doesn’t eat chicken, but you can go down the road a little ways and they’ll eat chicken, but they won’t eat pork,” Louis says. “It’s a matter of region.”

An aye-aye, strung up to ward off evil spirits. (Photo: Wikimedia Commons)

In one area of Madagascar, fady might protect the animals by making locals avoid the creatures out of fear. In another, it may lead people to kill aye-ayes and string them up at the edge of the village to ward off evil spirits. And then there’s a third scenario.

A few years ago, Louis and his colleagues were tracking a collar, but when they arrived at the nest, there was no aye-aye to be found. The tracking signal led them to a pile of fresh dirt nearby. Buried within was the collar, cut in two and dabbled in blood.

The team believes this particular animal was killed for its meat. That’s surprising, not only because of the stigma surrounding the aye-aye but also because Louis says the animals barely have any meat on them. The aye-aye is “all head and tail,” skin and bone.

“But if people are hungry, they’re going to eat,” Louis says.

Sadly, it’s not uncommon for lemurs to find their way onto the dinner plate. While the country is comparable in size to Sweden, Madagascar posts a Gross Domestic Product lower than countries such as Afghanistan and North Korea. More than 95 percent of the population lives on less than $2 a day. According to statistics provided by UNICEF, only 60 percent of children enrolled in first grade will complete their primary school education. And the numbers are even worse for secondary school.

Furthermore, almost 65 percent of the island nation’s inhabitants live in rural areas. In many of these places, people have learned to survive by slashing and burning the forest to make way for crops such as rice and manioc. This practice threatens already declining populations of endemic species, leads to erosion and pollution of water sources, and ultimately contributes to climate change. Similarly, hunting animals—even endangered ones—may be the only way some people have to supply their families with iron and protein.

“It’s very complex from a conservation point of view,” says Welch, who now serves as the conservation coordinator for the Duke Lemur Center. “You’re dealing with people who are just trying to feed their families.”

Because aye-ayes are so difficult to study, it’s tough to say how much of a threat fady killings or trade in bushmeat are to the survival of the species. But one thing is clear, Welch says: If there’s no forest, there will be no aye-aye.

Madagascar lost approximately 40 percent of its forest cover between the 1950s and 2000. While some of this destruction is to support trade in highly lucrative hardwoods like ebony and rosewood, Welch says most de-forestation is attributable to slash and burn agriculture.

Interestingly, traditional funeral rites in some areas may both save forests and contribute to negative sentiment toward aye-ayes. Wherever people are buried or laid to rest in tombs beneath rock overhangs, it’s forbidden to cut trees. Often, these stands are made up of canarium trees, which produce nuts that aye-ayes positively love. This means that some of the only places where people encounter aye-ayes are the equivalent of cemeteries—a coincidence that certainly doesn’t help the animal’s association with death.

“On more than one occasion we have seen aye-ayes strung up along the side of the road after being killed,” says Erik Patel, project director for the Duke Lemur Center’s SAVA Conservation Project.

Patel and his colleagues work to change the attitudes of locals by visiting rural villages and teaching kids about the animals around them. Additionally, the SAVA Conservation Project hopes to protect animals by directly improving the lives of people. The project sponsors re-forestation projects and training for teachers. They partner with human health and family planning initiatives, supply fuel-efficient stoves, and promote yams—which are more nutritious and weather-resistant—over traditional crops like manioc which take a heavier toll on the environment. They’ve even built a handful of aquaculture ponds to kick-start fish-farming programs that simultaneously provide people with much-needed protein and cut down on the need for bush meat.

Of over 101 lemur species, the International Union for the Conservation of Nature considers 90 of them to be threatened in some way, making lemurs the most imperiled mammals on Earth. And with Madagascar’s population expected to more than double by the year 2050, programs like the SAVA Conservation Project may be some of the only hope these species have in the face of extinction.

After a decade and a half of tracking and studying aye-ayes, Louis says he’s become attached to many of the animals. One in particular, an older female named Bozy (pronounced boo-zee), seems to have stolen his heart. “She’s just a really good mom,” Louis swoons.

But the feeling does not appear to be mutual. Louis says there have been times when they’re following her at night both by the collar’s signal and the shine given off by her eyes in a flashlight. Then all of a sudden, Bozy disappears. The last time she did it, Louis snapped a few photos in the dark that reveal the aye-aye’s trick.

“She’s got her eyes closed,” he says in disbelief. “I think she’s learned to close her eyes and keep on walking, and that’s how we lose her.”

Since it was first described in 1782, the aye-aye has gone from bad omen to evolutionary marvel, an animal unlike any other on the planet. We now think that its middle finger only warms up when its in use, that the species has the lowest level of genetic diversity of any primate on record, and that the need to hear its own tapping may have limited the aye-aye’s ability to communicate over long distances.

What more will be revealed about this fascinating creature before it shrugs off our surveillance and vanishes into the forest—perhaps one day for good?

Demon Week is Pacific Standard's series of essays exploring all things diabolical—from devils to dogs, monsters to mental illness.