The Northern muriqui is an endangered muriqui (woolly spider monkey) species native to Brazil. Muriquis are the largest species of New World monkeys. These monkeys have a thick fur that is light brown to gold in color. They have a large and round belly. Their long prehensile tail and long arms are an important adaptation for arboreal travel and feeding.
Northern muriquis are found in the Atlantic Forest region of the Brazilian states of Rio de Janeiro, Espírito Santo, Minas Gerais, and Bahia. These monkeys live in tropical moist forests.
Northern muriquis are arboreal and diurnal creatures. They move around through the canopy using brachiation with the help of their long arms and tail. In disturbed habitats, Northern muriquis spend more time on the ground. They come down to the ground to feed, rest, and socialize. Main forms of socializing are playing and embracing behaviors. Males usually spend more time on the ground than females. Northern muriquis are social and live in groups that consist of males, females and juveniles, and range from 48 to 81 individuals. These large multi-sex groups consist of smaller subgroups that feed and rest separately. Males usually spend most of the time in smaller all-male groups, which consist of 8-9 individuals. Females spend much time alone away from these male groups and other females, feeding alone or with offspring. They may associate more with other adult females than males when they are not mating. In order to communicate with each other Northern muriquis use different calls that are used for long and short distance communication. During vocalizations, muriquis answer the initial vocalizer in turn. This is called a sequential exchange.
Northern muriquis have a polygynandrous (promiscuous) mating system. This means that both males and females have multiple partners during each breeding season. Northern muriquis breed from October to April and infants are born from May to October. Females give birth to a single infant after the gestation period that lasts around 7 months. Infants depend on their mothers during the first year of life. At 3-6 months after birth infants cling their mothers' belly and later move on their back to travel. Young become independent from their mothers at the age of 2 years old. Females become reproductively mature at 5 to 11 years of age and leave their natal groups. Males attain reproductive maturity at 4 to 8 years of age.
Northern muriquis are threatened by hunting and destruction and fragmentation of their Atlantic Forest habitat. These animals also suffer from hunting and very low genetic diversity.
According to the IUCN Red List, in 2005 the total population size of Northern muriquis was around 855 individuals. Currently, this species is classified as Critically Endangered (CR) on the IUCN Red List and its numbers today are decreasing.
Northern muriquis feed on fruits and seeds, thus acting as important seed dispersers for different plants in the ecosystem they live.