Cacajao

• Their bald face can be red or black, depending on the species.
  The red face is an indicator of health and attractiveness for the females, who choose their mates based on the intensity of the color.

• Their short tail is unlike any other Neotropical monkey, and it may be an adaptation to their habitat of flooded or riparian forests.

• Their teeth are specialized for eating unripe fruits, which are abundant in their environment.
  They have narrow, forward-projecting incisors and enlarged canines, but small and low-crowned molars.

• Their social organization is based on fission-fusion dynamics, which means they split into smaller groups for foraging and rejoin at night.
  They can form large troops of up to 100 individuals, and they communicate with a variety of vocalizations.

There is a monkey called Cacajao
With a bald face and a short tail, oh no!
It lives in the Amazon, where the trees are tall
And eats fruits and seeds, both ripe and raw

Some people call it uakari or saki
But I think Cacajao is more wacky
It has red or black skin, depending on the kind
And it chooses its mate by the color of its rind

Cacajao is a rare and endangered primate
It needs our help to survive and mate
So let's protect its habitat and respect its right
To swing in the forest from morning till night