... Spider Monkey (Ateles Geoffroyi) ...
by Infocostarica Staff

The spider monkey's range is from the southern zone in Tamaulipas, Mexico to the Mato Grosso in Brazil. Some biologists divided the genus Ateles into four species. But for others there is only one specific name for Ateles that is valid (Ateles Paniscus).

There are nine subspecies of Ateles geoffroyi based upon variation in coat color. All of this species show dark fur on the dorsal sides of the forearms and the dorsal aspect of the hind limbs from the knee to the heel. Other parts of their body can variant, from blond like the ventrum, back, shoulders, and tail. This in the subspecies A.g. ornatusto almost black in A.g. pan. Within Costa Rica two subspecies are generally encountered, A.g.ornatus in the north and A.g. panamensis in the south.

The spider monkey is diurnally active and has a extreme specialization for an arboreal way of life. It can move rapidly through the trees, brachiating with its forelimbs and using even his tail to make easier the locomotion. The form of its brachiation is not the same to that shown by the gibbon. The body proportions give it its common name, just looking its limbs: long and slender. The tail is very prehensile and strong supporting the entire weight of the animal.

The gestation in this animal takes approximately 225 days. Intervals between births can range from 2 to 3 years. Lactation demands during the first year of the infant ´s life induce a lactation anestrus, and the female generally will not begin to cycle again until weaning is concluded.

When it is one year old the young animal weighs approximately 500g. It remains in intimate alliance with the mother for the first three months of life. Initially it is carried ventrally and about 1.5 to 2 months it begins to ride dorsally in the mother ´s body. The young will proceed to suckle from the mother until it is close to 1 year of age, although at this age it has begun to take significant solid food. The weaning process is slow, with solid foods being taken from about three months of age on. The age of weaning is possibly in part a business of the alimentary situation of the female and the young. Since the female produces only a single young and the interbirth period is changeable and extended, the reproductive rate of Ateles in the wild is very low. Thus wild populations of Ateles are slow to recuperate from any form of hunting. It appears that the genus Ateles is very susceptible to human perturbation of the habitat, and it may be among the first primate species to decline with severe disturbance.