Southern muriqui

Brachyteles arachnoïdes

SUBFAMILY

Atelinae

TAXONOMY

Ateles arachnoïdes (É. Geoffroy, 1806), Brazil. OTHER COMMON NAMES

English: Woolly spider monkey; French: Atèle arachnoïde, eroïde, singe-araignèe; Spanish: Mono grande, muriki.

PHYSICAL CHARACTERISTICS

Muriquis are distinguishable by their large body size, light pelage, elongated limbs, and prehensile tails. Southern muriquis have black faces and black genitalia, and are lacking a thumb. The canines of males are larger than those of females.

DISTRIBUTION

Atlantic forest within the states of Sao Paulo, Paraná, and probably Rio de Janeiro.

HABITAT

Semi-deciduous montane forest. BEHAVIOR

Behavioral data from two populations in Sao Paulo indicate substantial variation that is most likely related to ecological differences. At Fazenda Barreiro Rico, Milton (1985) observed a group of 7 individuals, including females and immatures. Females associated only loosely with adult males, except when a

female was sexually receptive and mated with multiple males in close succession. At Parque Estadual de Carlos Botelho, Moraes et al. (1998) described a larger group of over 20 individuals including adult males, females, and immatures that usually split up into smaller foraging parties. Low population densities at Carlos Botelho may account for the low frequency at which long-distance vocalizations are heard. Peaceful associations among group members, including adult males, seem to be an unusual behavioral feature of the genus.

FEEDING ECOLOGY AND DIET

Flexible grouping patterns allow southern muriquis to reduce competition over food, which includes primarily fruits, leaves, and flowers. In the large, continuous, more humid forest at the Parque Estadual Carlos Botelho, the majority of the diet is fruit, and home ranges may exceed 1,975 acres (800 ha). By contrast, in the smaller, drier forest at Fazenda Barreiro Rico, the diet is more seasonal and home ranges are much smaller.

REPRODUCTIVE BIOLOGY

Polygamous. Milton (1985) described the mating patterns of one female at Fazenda Barreiro Rico. This female exhibited proceptive behavior, including a distinct "mating twitter" vocalization, and copulated with multiple males in close succession over the course of a few days. Births appear to be concentrated during the dry season months. Milton described the large quantities of ejaculate visible after copulations, which have also been observed in northern muriquis.

CONSERVATION STATUS

Listed as Critically Endangered by the IUCN.

SIGNIFICANCE TO HUMANS

Although they are legally protected, hunters still seek adults for meat and infants as pets. ♦

Northern muriqui

Brachyteles hypoxanthus

Gray woolly monkey

Lagothrix cana

SUBFAMILY

Atelinae

TAXONOMY

Brachyteles hypoxanthus Kuhl, 1820, Bahia

OTHER COMMON NAMES English: Woolly spider monkey.

PHYSICAL CHARACTERISTICS

Northern muriquis are born with black faces, which become dispigmented with pink or white mottling as they mature. Male testes are also variable in color and mottling. Some possess vestigial thumbs, which together with their facial mottling, distinguish the northern species from the southern

DISTRIBUTION

Atlantic forest within the states of Minas Gerais, Espirito Santo, and probably still in southern Bahia.

HABITAT

Semi-deciduous montane forest. BEHAVIOR

Behavioral data are available from two populations in Minas Gerais, including one long-term study initiated in 1982 at Fazenda Montes Claros, now known as the Esta^ao Biológica de Caratinga/Reserva Feliciano Miguel Abdalla (EBC/RFMA). Strier (1999) documented an increase in one group's size from 22 to 70+ individuals over a 20 year period. Grouping patterns became more fluid as the number of group members increased, but adult males, which remain in their natal groups, routinely associate together in the same subgroups. Relationships among group members are strikingly peaceful and egalitarian.

FEEDING ECOLOGY AND DIET

Northern muriquis have highly seasonal diets corresponding to the availability of preferred fruits, flowers, and new leaves. They consume mature leaves, as well as bark and bamboo, primarily in the dry season when their preferred foods are

REPRODUCTIVE BIOLOGY

Polygamous. Using non-invasive fecal steroid analyses, Strier and Ziegler (1997) found that females at the EBC/RFMA experienced 2-6 ovarian cycles prior to conceiving, intervals between ovulations averaged about 21 days, and gestation lasted 7.2 months. Females routinely mate with multiple partners. The mating season begins at the end of the annual dry season, with the majority of conceptions occuring during the peak of the rainy season. Births are concentrated during the dry season, and interbirth intervals average three years.

CONSERVATION STATUS

Listed as Critically Endangered by the IUCN.

SIGNIFICANCE TO HUMANS

Although they are legally protected, hunters still seek adults for meat and infants as pets. ♦

SUBFAMILY

Atelinae

TAXONOMY

Simia cana (E. Geoffroy, 1812), Brazil.

OTHER COMMON NAMES English: Geoffroy's woolly monkey.

PHYSICAL CHARACTERISTICS

Grayer, with an even darker gray head compared to the brown woolly monkey Lagothrix lagotricha, whose head is lighter in color than its body. Lowland specimens may be paler gray; in all, hands, feet, and tails are darker than the body.

DISTRIBUTION

Brazil, south of the Amazon and Peru, southern highlands.

HABITAT

Gallery, flooded, and unflooded rainforest.

BEHAVIOR

Peres (1996) studied a group of 39-41 gray woolly monkeys in terre firme forest near the upper Urucu river in Amazonas, Brazil. Altogether, this group included nine adult and subadult males, 12-14 adult females with 5-8 infants, and 15-18 subadult females and juveniles. Group members spent most of their time spread out from one another, but in contrast to the fission-fusion societies of spider monkeys, their movements were not independent of one another and subgroups usually included a combination of adult males, females, and immatures. Gray monkeys use vocalizations, including a "loud neigh" to maintain contact with one another while spread out by more than 1,300 ft (400 m).

FEEDING ECOLOGY AND DIET

Gray woolly monkeys prefer fruits and flowers when these resources are available, but also eat a variety of foliage. They adjust the size of their feeding parties to the size of fruit and flower patches, and the degree to which they spread out while feeding coincides with seasonal variation in the density of fruit patches in their home range, which was estimated to exceed 2,220 acres (900 ha). Within their home range, they preferred unflooded forest to flood forest.

REPRODUCTIVE BIOLOGY

No data are presently available from wild populations.

CONSERVATION STATUS Listed as Vulnerable by the IUCN.

SIGNIFICANCE TO HUMANS A major source of meat in many areas. ♦

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