They are similar in appearance to the closely related lesser grison, from which they can be most readily distinguished by their greater size, with a head-body length ranging from 45 to 60 centimetres (18 to 24 in).

[2] The back, flanks, top of the head, and the tail, are grizzled grey in color, while the rest of the body is much darker, and usually solid black.

[4] They live alone or in pairs, with home ranges of at least 4.2 square kilometres (1.6 sq mi), and a very low population density, such that they are rarely encountered in the wild.

They have been reported to respond to threats with a series of grunts that rise in intensity and frequency until they become rapid barks, and finally a single loud scream with their teeth bared.

Newborn young weigh less than 50 grams (1.8 oz), and are initially blind, although with a short coat of hair already bearing the adult pattern.