About Ateles fusciceps Gray, 1866
This species, Ateles fusciceps, commonly known as the black-headed spider monkey, has two recognized subspecies with distinct coloration. The nominate subspecies A. f. fusciceps has a black or brown body and a brown head, while A. f. rufiventris is entirely black with some white markings on its chin. The black-headed spider monkey is one of the larger New World monkeys. Excluding the prehensile tail, head and body length typically ranges between 39.3 and 53.8 cm (15.5 and 21.2 in), while the prehensile tail itself measures between 71.0 and 85.5 cm (28.0 and 33.7 in). On average, males weigh 8.89 kilograms (19.6 lb) and females weigh 8.8 kilograms (19 lb), and the species' brain weighs an average of 114.7 g (4.05 oz). The two subspecies occupy different habitat types and elevation ranges. A. f. fusciceps lives in tropical and subtropical humid forests between 100 and 1,700 metres (330 and 5,580 ft) above sea level, with a recorded population density of 1.2 monkeys per square kilometer. A. f. rufiventris lives in dry forests, humid forests and cloud forests, and can occur at elevations up to 2,000 to 2,500 metres (6,600 to 8,200 ft) above sea level. In terms of reproduction, when mating, females may stay and mate with a single male for up to three days, or they may mate with multiple different males. Mating occurs face-to-face between the male and female, and typically lasts between five and 10 minutes. The gestation period for this species is between 226 and 232 days. After birth, the infant rides on its mother's back for 16 weeks, and is weaned at 20 months old. Females reach sexual maturity at 51 months, while males reach sexual maturity at 56 months. Females give birth once every three years. Captive black-headed spider monkeys are known to live more than 24 years. The International Union for Conservation of Nature (IUCN) classifies the black-headed spider monkey as Endangered. This classification is due to an estimated population loss of more than 50% projected over 45 years from 2018 to 2063, driven by hunting and human encroachment on the species' range.
