This is the indri, or, Indri indri, or babakoto.

This large species of lemur inhabits the tropical, moist, lowland and montane forests in the northeast of the island of Madagascar.
It was declared "critically endangered" in 2016, and is expected to see a population decline of around 80% by the year 2050.

Traditionally, the indri has been a sacred creature for the Malagasy people, who would neither hunt nor eat the animal. However, these taboos have been eroded in modern times, and now hunting for bushmeat is one of the major threats facing this species. There has also been widespread deforestation of the indri's habitat for agriculture, fuelwood and logging. The pandemic of 2020 and the following loss of livelihood for the island’s inhabitants has resulted in an accelerated rate of deforestation on the island, where just 10% of primary forest remains.

The Malagasy word for indri is “babakoto" - “baba” meaning “father” and “koto” meaning “boy” - the name literally translates as "father of a little boy”. It is often, however, simply translated as “ancestor".

Stories and myths featuring the indri often describe a shared origin with people - not surprising, given its many human-like characteristics: its long legs, upright body, lack of a prominent tail, and complex methods of communication.

One myth tells of a young boy who goes into the forest to collect honey. Whilst high in a tree, he is stung by bees and falls, but an indri catches him and carries him to safety.

There is also a story of two brothers who live together in the forest. One of them decides to leave the forest and tend to the land - this man becomes the first human. The brother who stays behind becomes the first indri, who cries in mourning for his lost sibling.

In another myth, a man fails to return from a hunting trip in the forest. His son, worried for him, sets out to try and find his father, but he also disappears. The other villagers go looking for the pair, only to find two large lemurs sitting in a tree: the father and son had transformed into the first indri. In some versions of the story, only the son transforms, and the father's cries for his lost son are analogous to the indri's mournful howls.
Each morning, as the sun rises, indri engage in a behaviour which is remarkably reminiscent of humans. They find an open position on a branch, and face the sun with legs crossed, back erect, hands placed on the knees with palms facing outwards, and eyes half-closed. This behaviour has been called "sun-worshipping", but this is perhaps an overly anthropomorphic term. The exact purpose of the activity is unclear.
The distinctive cry of the indri is a form of communication between two different groups, sequentially calling and responding, in songs that can last between 45 seconds and 3 minutes. The singing is dominated by the most senior pair of each group, but involves all members, apart from the very young. It is thought to communicate territorial boundaries, environmental conditions, reproductive status of the members, and warning signals. Indri sometimes sing after sonic disturbances such as thunder, passing airplanes, bird calls and other lemur calls.

The songs are performed from the top of the tree canopy, and can be heard up to 4 kilometers away.

Most songs have a pattern that consists of three phases: the "roar" sequence, which lasts for several seconds; the "long note" sequence, with notes up to five seconds in duration; and the "descending phrase" sequence, in which a high-pitched wail becomes progressively lower. This last phase is commonly coordinated between two indri to form a duet. Groups sing multiple times a day, but usually in the morning, and more often during the breeding season.

In addition to these songs, indri are known to vocalise in other ways, including sounds which scientists have named "hoot", "honk", "grunt", "kiss", "wheeze" and "hum". These calls have an unknown function and are still a focus of research.