The Indri Indri is the largest living lemur on Madagascar today. They do not survive in captivity, so to see them, you have to trek to where they live. There are two family groups of Indri you can see at Andasibe National Park in eastern Madagascar.
Indri live in small family groups with a monogamous mated pair and their children. The kids aren't mature to leave home until about 9 years old. Indri can easily live over 40 years.
They are famous for their very, very loud songs used to establish territory, to warn of danger, and to otherwise communicate with one another and between groups. The call of the Indri are generally heard each morning as the groups sing to each other regarding boundaries of their territories. The songs are similar to humpback whale songs, and interesting to listen to. They can be heard from quite a distance.
The Indri really look like fuzzy teddy bears. They have fuzzy ears and intense eyes and look cuddly, despite their very strong legs and long limbs. It's hard to get good photos since they are high in the trees and looking up at them from the rainforest floor doesn't offer great vantage points.
There were lemurs larger than Indri in the past, including one the size of a gorilla. Unfortunately, that and more than a dozen other lemur species were exterminated when man reached the island. That event, roughly 2,000 to 2,500 years ago, marked the beginning of the end for the lemurs as man began to cut down the forest, hunt the lemurs, and introduce all sorts of plants and animals not endemic to Madagascar. Today there are pockets of "original Madagascar" but often even those harbor many non-native species. What man has done to this beautiful island and its creatures is horrific, and really hard to see up close.
I saw both groups of Indri on two separate days at Andasibe. The only drawback is that it is a busy park, and everyone wants to see the Indri as it is one of the only parks you can view them. So, when you find them, there may be 20 other tourists staring up at them as well. When they start babbling and making noise to try and get the Indri to look at them it gets pretty revolting. So, I tried to find the groups before everyone else and leave when everyone else descending upon me, and had decent success with that.
The calls were very intense and fun to listen to. I could hear them from my hotel at Andasibe, F'eony Ala, and supposedly they can be heard by humans up to 1.2 miles away. If you want to get a sense of them there are some resources on the web, including some at You Tube (and here) with recordings of various quality.
The hotel was quite decent, with bungalows which had showers, toilets and even hot water and electricity. Also, though I didn't know it at the time, this place would prove to have the best food I was able to get in Madagascar.