23.1e – The Indriids

The lemurs of hip-hop. (Diademed Sifaka photo by Tom Junek)

In the mad, mad world of lemurs in Madagascar, we’ve looked at the tiny dwarf lemurs, the bizarre aye-aye, and the typical lemurids, but those aren’t all. There are even more types of lemurs sharing the treetops on this crowded island.

There are 19 different species of indriids, and we can roughly divide them into three types — the woolly lemur, the sifaka, and the indri. The basic thing that sets indriids apart from the other lemurs is that they are not very good at moving on the ground. An indriids hind legs are very much longer than their arms, and this means that they cannot move around on all fours, as the lemurids do.

To visualize their dilemma, try it yourself, for humans suffer the same problem. Try to move not on your hands and knees, but on your hands and feet. You will quickly see why indriids don’t really like to move around this way. But unfortunately for the indriids, they aren’t able to walk upright in the manner of humans either. What’s a poor indriid to do?

Well, for the most part they stick to the trees, where they are incredibly agile and can jump great distances with their long, powerful legs. But they don’t hesitate to use the ground when they have to. What they do is stand up tall on their hind legs, stick their arms in the air for balance, and hop.

The sifakas are the best at this, or at least the most interesting to watch. They take great, sideways leaps across the ground in order to cover distance as quickly as possible. I cannot embed videos on this blog, but if you would like to click on the following link it will open a new window in which you can see the sifaka doing its wonderful thing.

https://www.youtube.com/watch?v=f9ARvGS3mhk

The woolly lemurs are much like the sifakas, but the indri is the odd animal in the group — every family has at least one. The indri is one of the largest of all lemurs, measuring up to two and a half feet, not including its tail. The reason it’s not fair to include the tail is that the indri, well, does not really have one.

Every other type of lemur on the entire island has a magnificent tail, sometimes longer than the entire rest of its body. These tails are used for balance and sometimes for stink-fights, as we saw with the lemurids. But the indri has only a tiny knob of a tail, hardly even worthy of the name. Despite this balance handicap it still climbs and jumps around in the trees as well as anything, and still does the side-stepping hop-along movement on the ground.

No tail? No problem. (Indri photo by Erik Patel)

One interesting thing about the indri is that it is entirely monogamous. It is one of those rare species that mates for life; a mating pair will stay together and raise multiple generations of offspring — one at a time — until one of them dies, and will only then move on to seek a new partner.

Indris are very vocal, and different groups will “sing” to one another. Their songs can last several minutes at a time, and when one group is finished singing another group nearby may take up the tune. We aren’t entirely certain why they do it, but it may simply be a means of letting all the other indris know where they are. There doesn’t seem to be any one reason why they do it, however. Indris will sing after some loud noise has disturbed them, will sing to respond to other groups singing or even to other types of lemurs making noise, and sometimes will sing seemingly just because they want to. A group of indris might sing up to seven times a day, and their songs resemble in some ways those of humpback whales.

To hear what an indri’s song sounds like, give this link a gander: https://www.youtube.com/watch?v=4d3vFI5UpIc

In some ways the indri is one of the most advanced lemurs, and the natives of Madagascar treat it as a sacred animal. In local mythology, the indris and humans have close relationships. One myth tells the story of two brothers, long ago. One brother decided to leave the forest and cultivate the land, and he became the first human; the other brother stayed in the forest and the trees, and became the first indri. The myth says that the indris sing as a form of mourning for their long-lost brothers who left the forest.

And if that isn’t wonderful enough, the Malagasy people also believe that the indris worship the sun, much as a human would worship a god. There is a surprising amount of truth to this idea. Every morning when the sun rises, an indri will face it and sit cross-legged, back straight, palms in its lap or facing up, and watch the sun with eyes half-closed, the very image of a human in meditation. It is not believed by scientists that indris have enough social organization to actually be worshiping the sun, of course; it is most likely only a coincidental body posture and a desire to warm up in the morning. But it is wonderful all the same, and these strange, knob-tailed lemurs have a lot of surprisingly human-like features for being so far removed from us in the primate group.

Unfortunately, the indri is also endangered, highly threatened by habitat destruction. They do not survive in captivity, and have never been successfully bred, which means that without adequate protection this wonderful creature, and indeed many of the indriids, may someday soon leave our world forever. It is unfortunate that Madagascar combines at the same time such a rich diversity of species and such a lack of environmental protection, due to the material needs of a poverty-stricken society.

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