Thanks to the great variety and quantity of natural resources present in the tropical rainforests of the north and in the jungle, Peru is considered to be one of the countries with the greatest wealth of mammals and primates. There are 36 registered species and a further 3 endemic species: the yellow tailed woolly monkey (Oreonax flavicauda), the Andean titi monkey (Callicebuss oenanthe) and the Andean night monkey (Aotus miconax).
New World primates are grouped into three large taxonomic families: the Callitrichidae, which includes tamarins and marmosets; the Callimiconidae, whose sole representative is the goeldi false marmoset; and the Cebidae, the largest of the three, including squirrel monkeys, capuchins, titis, musmuquis, howler monkeys, woolly monkeys and spider monkeys, among others.
Monkeys from the Americas are distinguished from their European relatives by a series of morphological differences produced by their adaptation to tropical environments. The most obvious and visible of these is the configuration of the nose: American monkeys have a longer nose, with appendage nasal passages on either side and a point that curves down.
In the north, the white capuchin monkey (Cebus albifrons) inhabits some areas on the western slopes of the Andes (Piura and Tumbes departments) and the howler monkey of Tumbes (Alouatta palliata) is an exclusive resident of the most northern tropical Pacific jungles. 12 species of primate exist in the Pacaya-Samiria National Reserve, and 13 varieties inhabit the Manu National Park.
The size and weight of the primates varies, with the largest being the yellow-bellied spider monkey (Ateles belzebuth) and the black spider monkey (Ateles chamek), which weigh up to 11 kg and stand 1.5 metres tall from head to tail. The smallest barely measure 35 cm, such as the tamarins (Cebuella pygmea), which weigh 150 g. The majority feed on fruit, leaves and insects.