Mexican Spider Monkey

The Mexican spider monkey (*Ateles geoffroyi vellerosus*) is one of six recognized subspecies of the Geoffroy’s spider monkey (*Ateles geoffroyi*). Populations of the Mexican spider monkey occur in the Southern Mexican states of Veracruz, Oaxaca, Chiapas, Tabasco, Yucatan, and Quintana Roo. Farther south, beyond its eponymic country, this monkey is found in Guatemala, Belize, El Salvador, and Honduras. Spider monkeys occur in a variety of neotropical forested habitats throughout Central America, including cloud forest, tall evergreen forest, lowland tropical forest, mangrove forest, and dry deciduous forest. Although they can survive in forest remnants that have been disturbed by human activities, population studies and general species ecology suggest that spider monkeys are highly susceptible to the effects of habitat degradation. Spider monkeys, or members of the genus *Ateles*, are large-bodied primates that share consistencies in size and body proportions. Both sexes of the Mexican spider monkey grow similarly throughout life and at maturity possess nearly identical lengths and weights. Adults are 18.5 in (47 cm) long, excluding the dextrous, furred tail, which is longer than the body at 28 in (70 cm). Mature males typically weigh 17 lbs (7.8 kg), and female mass is 16 lbs (7.3 kg). In wild-living populations, individual longevity is strongly affected by habitat quality and susceptibility to local (human) hunting. Assuming infants reach adulthood, members of this species live around 25 years. In captivity, individuals may live significantly longer. One instance of a captive female reaching 47 years old is documented. The Mexican spider monkey has a highly variable color pattern, though variations are not determined by sex. The subspecies is monomorphic, meaning that males and females are nearly identical. Their fur is short and not dense. The majority of their coat, including the portions covering the head, limbs, hands, feet, and tail is brownish-black or black. The hair-coat lightens towards the lumbar region, on the underside, and on the inner aspects of the limbs. Coloring in these areas may range from silvery-white, to yellowish-white, to golden brown. Infants have a uniform, dusky pelage, which transitions into the bicolor pattern at the end of their first year of life. Due to species monomorphism, the sexes can be difficult to differentiate in the field. However, at a close range, females can be identified by their elongated clitoris or by the act of carrying an infant, a female-only activity. Spider monkeys have a smallish head and a large, pear-shaped, pot-bellied body. Their gracile limbs each possess four long digits and lack an external thumb. These “hook-like” hands are specialized for arboreal locomotion; in the trees, these monkeys adeptly grasp, hang, and swing on branches. The prehensile tail operates as a fifth limb that can support the entire body weight on its own. The end of the tail has a skin-textured strip that is used to grip objects and move in the trees. Their adaptable diet is based on regional and seasonal food availability. However, spider monkeys are primarily fruit specialists. Ripe fruit usually constitutes between 55% and 82% of the annual diet. Preferred fruits come from large- to medium-sized tree species that are distributed in clumps and have long fruiting periods. These conditions are ideal for feeding, since these large-bodied primates forage more easily on clusters of large, dense tree limbs where ripe fruits are plentiful and reliably available for sustained periods of time.