1300

Central American squirrel monkey

Central America

1300

Saimiri oerstedii

Endangered

The major threat to this species across its range is habitat loss, primarily due to agriculture and logging.

The Central American squirrel monkey or (Saimiri oerstedii), also known as red-backed squirrel monkey, is a squirrel monkey species from the Pacific coast of Costa Rica and Panama. It is restricted to the northwestern tip of Panama near the border with Costa Rica, and the central and southern Pacific coast of Costa Rica, primarily in Manuel Antonio and Corcovado National Parks. It is a small monkey with an orange back and a distinctive white and black facial mask. It has an omnivorous diet, eating fruits, other plant materials, invertebrates and some small vertebrates. In turn, it has a number of predators, including raptors, cats and snakes. It lives in large groups that typically contain between 20 and 75 monkeys. It has one of the most egalitarian social structures of all monkeys. Females do not form dominance hierarchies, and males do so only at breeding season. Females become sexually mature at 2½ years, and males at 4 to 5 years. Sexually mature females leave the natal group, but males can remain with their natal group their entire life. The Central American squirrel monkey can live for more than 15 years.

The Central American squirrel monkey population declined precipitously after the 1970s. This decline is believed to be caused by deforestation, hunting, and capture to be kept as pets. Efforts are underway to preserve the species. Despite the threats to the population, in 2008 the International Union for Conservation of Nature (IUCN) upgraded its conservation status from “endangered” to “vulnerable”.

The Central American squirrel monkey differs in coloration from South American squirrel monkeys. While South American squirrel monkeys tend to be primarily greenish in color, the Central American species has an orange back with olive shoulders, hips and tail, and white undersides. The hands and feet are also orange. There is a black cap at the top of the head, and a black tip at the end of the tail. Males generally have lighter caps than females. The face is white with black rims around the eyes and black around the nose and mouth. The two subspecies are similar in coloration, but differ in the shade of the cap. The northern subspecies, living in Central Pacific Costa Rica, has a lighter cap than the southern subspecies, which lives in Panama and in parts of Costa Rica near Panama. The southern subspecies also has more yellowish limbs and underparts. Adults reach a length of between 266 and 291 millimetres (10.5 and 11.5 in), excluding tail, and a weight between 600 and 950 grams (21 and 34 oz). The tail is longer than the body, and between 362 and 389 mm (14.3 and 15.3 in) in length. As with other squirrel monkeys, there is considerable sexual dimorphism. On average, males weigh 16% more than females. Males have an average body weight of 829 g (29.2 oz) and females average 695 g (24.5 oz). Squirrel monkeys have the largest brains of all primates relative to their body size; the Central American squirrel monkey’s brain weighs about 25.7 g (0.91 oz), or about 4% of its body weight. Unlike larger relatives, such as the capuchin, spider and howler monkeys, Central American squirrel monkeys do not have a fully prehensile tail, except as newborn infants, and the tail is primarily used to help with balance.