Spix's Red-handed Howler Monkey

Spix's red-handed howler has a similar appearance to the red-handed howler, but it has a yellowish-brown to reddish-brown back. Males weigh about 7.2 kg, females about 5.5 kg.

The species is endemic to central Brazil, specifically along the southeastern Amazon River in the State of Pará. It occurs mainly in the interfluvial land area between four rivers, Tapajós, Juruena, Xingú and Irirí. The westernmost limit of native habitat lies on the right bank of the Tapajós River and Juruena River and stretches east to the banks of the Xingú River and Irirí River. This strip of land extends northward to Forte Curupá (Gurupá), Brazil, which is the northernmost extent of the distribution of Spix's red-handed howler and also its type locality. Spix's red-handed howler mainly inhabits lowland forests separated by dry areas as well as forests affected by seasonal flooding.

The primary food source of this species is ripe and unripe fruit; it has the highest reliance on this food source of all species in this genus. A variety of species provide fruit year-round, but leaves supplement the sugars of the fruits with protein in their diets. When these food sources are limited, the howlers also supplement their diets with more mature leaves, flowers, woody plant matter, and sometimes fungi to possibly help digest the increased plant matter. Spix's red-handed howlers generally move in groups of 4-11 individuals, and have relatively small home ranges, 5-45 ha in size.