Douroucouli/Night Monkey Aotus species

The Douroucoulis, also called Night Monkeys and Owl Monkeys, as the name indicates, are active at night. They are small monkeys native to jungles/forests of Central and South America.

Spix's Night Monkey
Spix's Night Monkey
The several species of Night Monkey are divided into two groups, the red-necked, further down the page, with ginger chest fur, and the grey-necked above and immediately below. Spix's Night Monkey, Aotus vociferans, is in the grey-necked group.
Spix's Night Monkey
Spix's Night Monkey
Spix's Night Monkey
Spix's is native to southern Colombia, eastern Ecuador, part of far northern Peru and northwestern Brazil.
  
Douroucouli
Night Monkey Azara's
Owl Monkey Bolivian
Above is the Bolivian subspecies of Azara's Night Monkey, Aotus azarai/azarae boliviensis. Like other Night Monkeys, it lives in mainly monogamous pairs with the father taking on most parental care of offspring. Apologies for poor pictures but I don't like to use flash on animals.
  
Black-headed Night Monkey
Black-headed Night Monkey
Above is the Black-headed Night Monkey, Aotus nigriceps, native to Bolivia, Peru, Colombia and Brazil. Tame and active in daylight in a park in Peru.