howler monkey

Howler monkey[1]
Black Howler Alouatta caraya
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Primates
Family:	Atelidae
Subfamily:	Alouattinae Trouessart, 1897 (1825)
Genus:	Alouatta Lacepede, 1799
Type species
Simia belzebul Linnaeus, 1766
Species
Alouatta arctoidea Alouatta belzebul Alouatta caraya Alouatta coibensis Alouatta discolor Alouatta guariba Alouatta juara Alouatta macconnelli Alouatta nigerrima Alouatta palliata Alouatta pigra Alouatta puruensis Alouatta sara Alouatta seniculus Alouatta ululata

Howler monkeys (genus Alouatta monotypic in subfamily Alouattinae) are among the largest of the New World monkeys. Nine species are currently recognised. Previously classified in the family Cebidae, they are now placed in the family Atelidae. These monkeys are native to South and Central American forests. They live in groups of usually about 18 individuals. Threats to howler monkeys include being hunted for food and captivity.

Classification

• Family Atelidae
  • Subfamily Alouattinae
    • A. palliata group
      • Coiba Island Howler, Alouatta coibensis
        • Alouatta coibensis coibensis
        • Azuero Howler Monkey, Alouatta coibensis trabeata
      • Mantled Howler, Alouatta palliata
        • Ecuadorian Mantled Howling Monkey, Alouatta palliata aequatorialis
        • Golden-mantled Howling Monkey, Alouatta palliata palliata
        • Mexican Howling Monkey, Alouatta palliata mexicana
      • Guatemalan Black Howler, Alouatta pigra
    • A. seniculus group
      • Ursine Howler, Alouatta arctoidea
      • Red-handed Howler, Alouatta belzebul
      • Spix's Red-handed Howler, Alouatta discolor
      • Brown Howler, Alouatta guariba
        • Northern Brown Howler, Alouatta guariba guariba
        • Southern Brown Howler, Alouatta guariba clamitans
      • Juruá Red Howler, Alouatta juara
      • Guyanan Red Howler, Alouatta macconnelli
      • Amazon Black Howler, Alouatta nigerrima
      • Purus Red Howler, Alouatta puruensis
      • Bolivian Red Howler, Alouatta sara
      • Venezuelan Red Howler, Alouatta seniculus
      • Maranhão Red-handed Howler, Alouatta ululata
    • A. caraya group
      • Black Howler, Alouatta caraya
  • Subfamily Atelinae

Anatomy and physiology

Howler monkeys have a short snout, and wide-set, round nostrils. They range in size from 56 to 92 cm, excluding their tail which can be equally as long. Like many New World monkeys, they have prehensile tails. Unlike other New World monkeys, both male and female howler monkeys have trichromatic colour vision.^[2] This has evolved independently from other New World monkeys due to gene duplication.^[3] They have a lifespan of 15 to 20 years.

Locomotion

They move quadrapedally and do not brachiate, usually holding on to a branch with at least two hands or one hand and the tail at all times. Their prehensile tails are strong enough to support the monkey's entire body weight, although they seldom do so. They very seldom leave the trees. They rest about 80 percent of the time and are considered the least active of all monkeys.

Behavior

Social systems

Howler monkeys live in groups where the number of females is greater than the number of males. Groups may have only one male or several males. Unlike most New World monkeys, juveniles of both genders emigrate from their natal groups,^[4] so neither adult males nor adults females in a group are typically related. Fighting among group members is infrequent and generally of short duration. However, serious injuries can result. Both males and females may fight with each other.^[4][5] Group size varies by species and by location, with an approximate male to female ratio of a male to four females.^[4]

Communication

As their name suggests, vocal communication forms an important part of their social behavior. They have an enlarged basihyal or hyoid bone which helps them make their loud sound. They are considered the loudest land animal. According to Guinness Book of World Records, it can be heard clearly for 3 miles (4.8 km).

Diet and feeding

These large, slow moving monkeys are the only folivores of the New World monkeys. Howlers eat mainly top canopy leaves, together with fruit, buds, flowers, and nuts. They need to be careful not to eat too much of certain species of mature leaf in one sitting, as some of the leaves they eat contain toxins that can poison the monkey.^[6] Howler monkeys are also known to occasionally raid birds nests and chicken coops and consume the eggs. ^[7]

Relationship with humans

A pair of howler monkeys

While seldom aggressive, howler monkeys do not take well to captivity and are of surly disposition, and hence are the only monkey in their forests not made a pet by the Native Americans^{[citation needed]}. However, the Black Howler (Alouatta caraya) is a relatively common pet monkey in contemporary Argentina due to its gentle nature, in comparison to the capuchin monkey's aggressive tendencies, in spite of its lesser intelligence as well as the liabilities meant by the size of its droppings and the males' loud vocalisation.

Alexander von Humboldt said about howler monkeys that "their eyes, voice, and gait are indicative of melancholy", while John Lloyd Stephens described those at the Maya ruins of Copán as "grave and solemn as if officiating as the guardians of consecrated ground". To the Mayas of the Classic Period, they were the divine patrons of the artisans, especially scribes and sculptors. Copán in particular is famous for its representations of Howler Monkey Gods. Two howler monkey brothers play a role in the 16th century myth of the Maya Hero Twins included in the Popol Vuh.

Gallery

Male Mantled Howler, Costa Rica

Howler, Costa Rica

Howler, Belize

References

External links

Wikispecies has information related to: Alouattinae

Wikispecies has information related to: Alouatta

Wikimedia Commons has media related to: howler monkeys

• Primate Info Net Alouatta Factsheets
• Howler monkey audio recording
• Information about howler monkeys from Belize Zoo (photos, video and audio included)
• "The Loudest Animal in the New World," Smithsonian National Zoological Park