Yucatán black howler males are larger than those of any other Central American monkey species.

Adults of both sexes have long, black hair and a prehensile tail, while infants have brown fur.

[7] Population density can exceed 250 monkeys per square kilometer in the Community Baboon Sanctuary in Belize.

[2] The Yucatán black howler's diet includes mostly leaves and fruit.

Threats to the species include habitat loss, hunting, and capture as pets.

[2][10] A theory for how this sympatry occurred and why the Yucatán black howler has such a restricted range is the ancestors of the Yucatán black howler and the Central American squirrel monkey migrated to Central America from South America during the late Miocene or Pliocene.

However, passage through the Isthmus of Panama then closed for a period due to rising sea levels, and later opened up to another wave of migration about two million years ago.

These later migrants, ancestors to modern populations of white-headed capuchins, mantled howlers and Geoffroy's spider monkeys, out-competed the earlier migrants, leading to the restricted range of the Yucatán black howler (and the Central American squirrel monkey).