SILVERY WOOLLY MONKEY
Lagothrix lagothricha poeppigii
Geographic Distribution and Habitat
The silvery woolly monkey (Lagothrix lagothricha poeppigii), also known as Poeppig’s woolly monkey, red woolly monkey, lowland woolly monkey, and chronogo (in Spanish), is found in western Brazil, eastern Ecuador, and northeastern Peru. They inhabit several different types of forest, including tropical lowland rainforest, cloud forest, and seasonally flooded forest. They live only in primary forest—disturbed secondary forests do not make good habitat for this species. Primary rainforest (forest that has remained relatively undisturbed from activities such as logging and agriculture) often has a full canopy, several layers of understory, and a relatively clear forest floor—because so little light, which is necessary for plant growth, penetrates the thick canopy. Secondary forest, which is formed when a forest is disturbed (such as through selective logging, slash-and-burn agriculture, or a forest fire), has a less developed canopy, smaller trees, more vegetation on the forest floor, and less diversity than a primary forest. Even mildly disturbed forests can significantly impact a population of woolly monkeys; therefore, undisturbed primary forest is a necessity for their long-term survival as a species.
Because study of silvery woolly monkeys specifically is rather limited, some of the information in this article relates to the genus as a whole and can be applied to all woolly monkeys including the silvery woolly monkey. We make that clear by using the term “woolly monkey(s)” when referring to the genus, and “silvery woolly monkey(s)” when referring to this species (or subspecies).
Woolly Monkey Taxonomy Controversy: Species vs Subspecies
Some scientists recognize the silvery woolly monkey (Lagothrix poeppigii), the gray woolly monkey (L. cana), and the Colombian woolly monkey (L. lugens) each as distinct species, sharing the genus Lagothrix.
Per a March 2020 report found in the International Union for Conservation of Nature’s (IUCN) Red List of Threatened Species, recent genetic studies have provided support for there only being only two woolly monkey species: the brown (or common) woolly monkey (Lagothrix lagothricha) and the Peruvian yellow-tailed woolly monkey (Lagothrix flavicauda).
In this scenario, silvery, gray, and Colombian woolly monkeys are subspecies of the brown woolly monkey (Lagothrix lagothricha). This modifies their scientific names to Lagothrix lagothricha ssp. cana for the gray woolly, Lagothrix lagothricha ssp. lugens for the Colombian woolly, and Lagothrix lagothricha ssp. poeppigii for the silvery woolly. There is also a fourth potential subspecies of the brown woolly, Lagothrix lagothricha ssp. tschudii, Tschudi’s woolly monkey. (Very little is know about this fourth subspecies.)
The truth is that the woolly monkeys don’t care what we call them. They would certainly prefer that we leave them and their habitats alone and allow them to quietly live their lives. But we hope to allay any confusion you might encounter in your reading should you come upon conflicting scientific names, terminology, and taxonomy.
Size, Weight, and Lifespan
The head and body of adult female silvery woolly monkeys are about 19 inches (49 cm) long, while adult males are about 20 inches (50 cm) long. Their tails are about as long, or slightly longer, than their head and body combined. Adult females weigh, on average, 10 lbs (5 kg), and adult males weigh 15 lbs (7 kg) on average, although their weight can fluctuate seasonally. They are one of the largest species of New World monkeys. In the wild, individuals can live over 30 years.
Silvery woolly monkeys are large monkeys with long, prehensile tails. Their arms are about as long as their legs. Their fur is extremely thick and woolly, and is reddish-brown in color, with dark brown-black on their head, hands, and feet. They often also have a slight silver sheen to their fur, hence their name. They have thickened pads on the ends of their tails that allow them to more easily grip branches.
The silvery woolly monkey is largely frugivorous, with a diet composed of about 77–79% fruit, 15–16% animal prey, and 5–6% leaves. During seasons when fruit is more scarce, silvery woolly monkeys increase their consumption of leaves and flowers. They eat the fruits of more than 250 species of plants, and they favor figs and guava shrubs.
Behavior and Lifestyle
Woolly monkeys use their tail extensively to move around. They often run and climb using both hands and feet, swing from their tail, and engage in brachiation. Occasionally they walk bipedally, although this is rare. They travel about 1 mile (2 km) per day, mostly staying in the forest canopy. Their home range can be between about 250 and 320 acres.
Silvery woolly monkeys are diurnal, and spend about equal parts of their day eating and foraging, moving, and resting. During seasonal fruit shortages, they spend less time moving and socializing, and more time resting.
Daily Life and Group Dynamics
Social groups of silvery woolly monkeys are typically quite large, averaging about 23 individuals. They are multi-male multi-female groups that can be flexible, with smaller “subgroups” sometimes breaking off for days at a time before returning. Typically, however, these subgroups will continue to travel with the main group and stay in contact through vocalizations.
Individuals bond through grooming, which is most often directed at adult males. Aggression between group-mates can occur, usually between females. Adult males usually avoid each other, especially while feeding.
Both males and females break off from groups to disperse and form or join new groups, although females are more likely to disperse than males.
What Does It Mean?
Specific calls that individuals in a troop make to warn other members of their group of imminent danger—such as predators.
Relating to the anus and genital region.
A biped is an animal that walk on two legs. Bipedally refers to animals moving on two legs. This comes from the Latin meaning “two feet.”
Also called arm swinging, is a form of arboreal locomotion in which primates swing from tree limb to tree limb using only their arms.
Disturbed secondary forest:
Disturbances refer to events that upset a habitat resulting in substantial impact. Disturbances include windstorms, logging, fire, and floods. A secondary forest is a forest that has re-grown after a major disturbance, such as fire or timber harvest, but has not yet reached the mature state of primary forest.
Active during daylight hours.
The time of pregnancy from conception until birth.
Multi-male multi-female group/unit (MMU):
A social group consisting of multiple adult males and multiple adult females.
New World monkey:
Monkeys native to Central and South America.
Able to grasp or hold objects.
Also termed old-growth forest, virgin forest, or primeval forest—a forest that has attained great age without significant disturbance and thereby exhibits unique ecological features and might be classified as a climax community, an ecological community in which populations of plants or animals remain stable and exist in balance with each other and their environment.
Visit the Glossary for more definitions
Silvery woolly monkeys communicate vocally and through scent. In the closely related brown woolly monkey, vocalizations can be broken down into three types: contact calls, which provide information about the location and distance between individuals; alarm calls; and social interaction calls. Similar forms of communication can be assumed about the silvery variety. Woolly monkeys leave scent marks by wetting a surface with saliva then rubbing their chest on it. They may also leave scent marks by dragging their anogenital region along a branch.
The scientific name of this species, Lagothrix poeppigii, is named for Eduard Friedrich Poeppig (1798–1868), a German naturalist and explorer who is credited with describing hundreds of new species.
Reproduction and Family
Silvery woolly monkeys reach sexual maturity at around four years of age but don’t typically give birth until about nine years of age. Both male and female silvery woolly monkeys have more than one mate. A female usually demonstrates her receptivity to mating by shaking her head and baring and chattering her teeth at a male. Although mating occurs year-round, births usually follow a seasonal pattern. For example, in Macarena-Tinigua National Park in Colombia, births of the closely related brown woolly monkey occur between July and December. This is because, although mating can occur year round, mating frequency peaks between December and May. The gestation period is about 225 days. Usually only one offspring is born at a time, although twins and triplets are possible. Babies are carried by the mother and are weaned at about one year of age.
Silvery woolly monkeys have relatively few predators, besides humans, owing to their large size. However, juveniles serve as a food source for large raptors. The daily activities of the monkeys stir up insects, which serve as food for double-tooth kites, a small raptor, and these species are often found near each other. Woolly monkeys are also very important for seed dispersal, and a single dropping can contain over 1,000 individual seeds.
Conservation Status and Threats
The silvery woolly monkey is classified as Endangered by the International Union for Conservation of Nature (IUCN, 2020) appearing on the IUCN Red List of Threatened Species. It is just a single step away from being Endangered. The silvery woolly monkey population is suspected to have undergone a reduction of 50% or more over a period of 45 years (three generations), likely due in part to the loss of suitable habitat. In addition, and perhaps more importantly, this species is very heavily hunted for its meat, as well as for the pet trade. According to studies population densities of heavily-hunted woolly species can be expected to decline by more than half over several generations.
Primary threats to silvery woolly monkeys are hunting and habitat loss. They are the single most frequently hunted primates in the Amazon region, mainly due to their large size resulting in their being relatively easy targets. The meat of woolly monkeys has been eaten by Amazonian communities for thousands of years. Traditionally, the meat was consumed mainly during festivals, although the meat is becoming increasingly popular in the illegal bushmeat trade throughout the region. As hunting technology improves, human population density increases, and Amazonian communities become more sedentary than nomadic, woolly monkey populations become increasingly threatened in areas near human settlements. As a result, some Amazonian people make expeditions into national parks and reserves to hunt and supply meat for festivals. In these protected areas, the monkeys are unaccustomed to human encounters and are less cautious and easier to hunt, sometimes not reacting to human presence or even coming closer in an attempt to threaten hunters. In many cases, after a mother is killed, her infant will be taken and sold as a pet.
Habitat loss is of particular threat to the silvery woolly monkey, as they do not adapt well to secondary forest. Most habitat loss affecting this species is a result of small-scale agriculture.
Climate change also poses a potential threat to woolly monkeys. The changing climate may cause trees to flower and fruit at different times of year. Woolly monkeys, who are extremely dependent on fruit availability, move around to follow the fruiting of different trees at varying elevations. The desynchronization of fruiting cycles may cause significant stress to members of the species as they struggle to find adequate amounts of food. As climate change progresses and more research is conducted, we may find more ways that silvery woolly monkeys are impacted by this global phenomenon.
This species is listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) to control its international trade. It is protected by almost 7 million acres of protected areas, an area about the size of the state of Hawaii. While this area is large, it is not continuous, and is instead split up into eight different national parks throughout Brazil, Ecuador, and Peru. Despite these protected areas, hunting, including illegal poaching, still persists.
- Stevenson, P. R. 2009. Estimates of the number of seeds dispersed by a population of primates in a lowland forest in Western Amazonia. In Seed dispersal: theory and its application in a changing world (pp. 340–362).
- Mayor, P., M. Bowler, and C. López-Plana. 2012. Ovarian functionality in Poeppig’s woolly monkey (Lagothrix poeppigii). Animal Reproduction Science 136(2013): 310-6.
- Walder, C. 2014. Rehabilitation Assessment of a Juvenile Woolly Monkey (Lagothrix lagotricha poeppigii) Troop on Sumak Allpa Island, Ecuador. SIT Digital Collections. Accessed 11 August 2019 at https://digitalcollections.sit.edu/cgi/viewcontent.cgireferer=https://scholar.google.com/&httpsredir=1&article=2878&context=isp_collection
- Di Fiore, A. and P.S. Rodman. 2000. Time Allocation Patterns of Lowland Woolly Monkeys (Lagothrix lagotricha poeppigii) in a Neotropical Terra Firma Forest. Internation Journal of Primatology 22(3).
- C. A. Peres. 1991. Humboldt’s woolly monkeys decimated by hunting in Amazonia. Cambridge University Press 25(2).
Written by K. Clare Quinlan, August 2019. Taxonomy and conservation status updated July 2020.