Alouatta palliata (Gray, 1849)

Taxonomy and Appearance Comparison

The mantled howler, scientifically named Alouatta palliata (Gray, 1849), shares a similar overall appearance with other howler monkeys in the genus Alouatta, and differs primarily in coloration.

Coloration Features

Its body is mostly black, with a fringe of yellow or golden brown guard hairs along its flanks; this feature gives the species its common "mantled" name. When males reach maturity, their scrotum turns white.

Body Length

Excluding the tail, female body length ranges from 481 to 632 mm (18+7⁄8 to 24+7⁄8 inches), while male body length ranges from 508 to 675 mm (20.0 to 26.6 inches). Its prehensile tail measures between 545 and 655 mm (21.5 to 25.8 inches) in length.

Body Weight

Adult females generally weigh between 3.1 and 7.6 kg (6+7⁄8 to 16+3⁄4 pounds), and adult males typically weigh between 4.5 and 9.8 kg (9 pounds 15 ounces to 21 pounds 10 ounces). Average body weight can vary significantly between populations from different locations.

Brain Characteristics

The brain of an adult mantled howler weighs around 55.1 g (1+15⁄16 ounces), which is smaller than the brain of several smaller monkey species, such as the white-headed capuchin.

Diet and Adaptations Overview

Like other howler monkey species, the mantled howler has specific adaptations that support its folivorous diet, which consists of a large proportion of leaves. Its molars have high shearing crests that help process leaves, and males have an enlarged hyoid bone near the vocal cords.

Hyoid Bone Function

This bone amplifies males' calls, allowing them to locate other males without expending much energy.

Native Range

The mantled howler is native to Colombia, Costa Rica, Ecuador, Guatemala, Honduras, Mexico, Nicaragua, Panama and Peru.

Distribution in Central America

Within Honduras, Nicaragua, Costa Rica and Panama, it is found across most areas of these countries.

Distribution in Colombia and Ecuador

In Colombia and Ecuador, it occupies a narrow corridor that borders the Pacific Ocean to the west and the Andes Mountains to the east; there is also a small population of the species in Colombia in a Caribbean coastal area near the Panama border.

Distribution in Guatemala and Mexico

In Guatemala, it lives across the central part of the country, and extends into southeastern Mexico, south of the Yucatán Peninsula.

Presence in National Parks

It is among the most commonly seen and heard primates in many Central American national parks, including Manuel Antonio, Corcovado, Monteverde and Soberania.

Habitat Preferences

It can live in several different forest types, including secondary forest and semi-deciduous forest, but occurs at higher densities in older forest areas and regions with evergreen forest.

Sympatry with Other Howler Species

Over a small portion of its range in Guatemala and Mexico near the Yucatan Peninsula, it is sympatric with another howler monkey species, the Guatemalan black howler, A. pigra.

Mating System

Mantled howlers have a polygamous mating system, where one male mates with multiple females. Usually, the group's alpha male monopolizes all breeding opportunities.

Male Mating Opportunities

However, if the alpha male is distracted, lower-ranking males can sometimes mate, and lower-ranking males get regular mating opportunities and sire offspring in some groups. Alpha males typically hold their status for 2+1⁄2 to 3 years, during which they may father around 18 infants.

Sexual Maturity Age

Females reach sexual maturity at 36 months old, while males reach sexual maturity at 42 months old. Females usually give birth to their first infant when they are 42 months old.

Estrus Cycle Characteristics

Females experience regular estrus cycles, with an average duration of 16.3 days, and show visible changes to their sexual skin, most notably swelling and a color change from white to light pink of the labia minora.

Mating Behavior

Mating begins when a receptive female approaches a male and performs rhythmic tongue flicking. The male responds with the same tongue movements, after which the female turns and elevates her rump to allow mating to start.

Chemical Mating Signals

Females also appear to use chemical signals, as males smell females' genitals and taste their urine.

Gestation and Birth Seasonality

The gestational period is 186 days, and births can happen at any time of year.

Infant Fur Development

Newborn infants have silver fur, which turns pale or gold after a few days. The fur then gradually darkens, and infants develop full adult coloration at around 3 months old.

Early Infant Caring Behavior

For the first 2 to 3 weeks of life, the infant clings to its mother's chest and is carried underneath her. After this period, it is carried on the mother's back.

Juvenile Independent Movement

At around 3 months old, the mother usually begins encouraging the infant to move independently, but will still carry it part of the time until it is 4 to 5 months old. After the young monkey can move on its own, the mother will still carry it across large, difficult gaps between trees.

Juvenile Social Behavior

Juveniles spend much of their time playing with other juveniles.

Weaning and Birth Interval

Infants are weaned at 1+1⁄2 years old, at which point maternal care ends. If a previous infant survives to weaning, adult females typically give birth every 19 to 23 months.

Male Reproductive Development

Unlike other howler monkey species, male mantled howlers' testes do not descend until they reach sexual maturity.

Natal Group Dispersal

Upon reaching sexual maturity, most young monkeys are evicted from their natal group, though the offspring of high-ranking females may be allowed to stay. Many infants do not survive to sexual maturity: high-ranking adults sometimes harass or kill the offspring of lower-ranking monkeys to eliminate competition for their own offspring when they reach maturity.

Emigration Rates

Both sexes leave their natal group; 79% of all males and 96% of all females emigrate from their original social group.

Infanticide by Incoming Males

When an outside male ousts the existing alpha male, he normally kills all existing infants in the group, so that the mothers quickly enter estrus and can mate with him.

Infant Predation and Survival Rate

Predators including cats, weasels, snakes and eagles also kill infants. As a result, only around 30% of mantled howler infants live longer than one year.

Reproductive Success Factors

Middle-ranking females have the highest reproductive success, while alpha females have lower success, likely due to competitive pressures. Infant mortality is also lower when multiple females in a group give birth around the same time.

Lifespan

If an individual survives infancy, it typically has a lifespan of 25 years.

Tool Use Observations

Tool use has never been observed in mantled howlers, and no howler monkey species was recorded using tools prior to 1997. In 1997, however, a Venezuelan red howler (Alouatta seniculus) was reported to use a stick as a club to hit a Linnaeus's two-toed sloth (Choloepus didactylus) resting in its tree. This observation suggests that other howler species, including the mantled howler, may also use tools in ways that have not yet been documented.