Alouatta seniculus have the widest geographical distribution of all the New World primates. Red howler monkeys range throughout the northern half of South America, from Colombia to Bolivia. Alouatta seniculus are slightly sexually dimorphic. Females have a body length of centimeters; males, which are larger, have a body length of cm. Both sexes have a long, prehensile tail of approximately cm.

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Alouatta seniculus have the widest geographical distribution of all the New World primates. Red howler monkeys range throughout the northern half of South America, from Colombia to Bolivia. Alouatta seniculus are slightly sexually dimorphic. Females have a body length of centimeters; males, which are larger, have a body length of cm. Both sexes have a long, prehensile tail of approximately cm.

The coat color of males and females is a deep reddish-brown, although the shade varies slightly with age. Red howlers have a large neck with tremendous lower jaw and hyroid bones, giving them a forbidding expression. Due to such an unbalanced sex ratio, fierce sexual competition exists between and within red howler troops. Red howler males, which are expelled from their natal troop upon reaching sexual maturity, are forced to invade an outside group and gain admittance.

Once they have accomplished this, they violently kill any infants present in the group. By killing infants in a newly invaded troop, a male can mate quickly and ensure that the new offspring of the group are his own. Mothers do try to protect their offspring against assaulting males. The mating behavior of red howlers is another interesting aspect of their social interactions.

Males and females often form consortships, an unusually close spatial relationship, before any sexual exchange has begun. Once these associations are established, sexual solicitations begin. Although seductive behaviors can be performed by both sexes, the female most often takes on the aggressive role. When attempting to attract a male, the female approaches him and moves her tonque rhythmically. The male may respond the same way, but if he does not, the female may simply try to entice another male.

Alouatta seniculus appears to breed throughout the year. However, in two habitats in Venezuela, the birth frequency is reduced during the early wet season, May through July. The estrous cycle ranges from days, with the female being receptive for days. Red howler females give birth for the first time around 5 years of age, while males usually do not father an offspring until approximately 7 years. Therefore, a female reaches sexual maturity a couple of years before a male.

Newborn A. Young red howlers begin using their prehensile tails before they are one month old. An infant uses its tail to secure itself to its mother, for in this stage of its life the mother pays little or no attention to her offspring, and fails to give the baby any assistance!

Red howler monkeys live in relatively large social groups, consisting of approximately 10 individuals, with only one or perhaps two of the individuals being males. Alouatta seniculus exhibit many interesting behaviors. They are most famous for their "dawn chorus", a deafening roar that can be heard up to 5 kilometers away!

These resonating howls, performed primarily by the males of a group, are answered by all other howler troops within ear shot. This way, one troop can constantly inform another of its precise location, thus avoiding an energetically costly squabble over resources.

During parturition, a newborn usually becomes the focus of attention of several other females. Typically, it is females without infants of their own that are attracted to these infants.

In these instances, the females are extremely gentle with the little ones, touching them with their muzzles and hands. They may even occasionally encourage the infant to crawl on them. Males also are known to tolerate the activities of infant howlers in their troop.

Similar to the adult females, the male red howlers also allow the infants to climb all over them. This of course takes place long after the male has killed all offspring that are not his own. Alouatta seniculus are primarily folivorous. Leaves are low in nutrients and sugars in comparison with other food choices, and red howler monkeys have two large sections in their hindgut which contain the bacteria needed to digest the cellulose in leaves.

This change in anatomy results in a large gut that occupies one-third of their total body volume. In addition, their extremely deep lower jaw bones aid red howlers in chewing. Alouatta seniculus also improve their digestive efficiency by feeding primarily on tender young leaves and on some species of leaves that are unusually nutritious.

In addition, they eat sugary fruits and flowers when these are available, but can sustain themselves for weeks at a time on only leaves, providing these are high in quality.

Alouatta seniculus spend almost their entire lives near the top canopy of the forest, where such leaves are most abundant Devore, MacDonald, Due to their relatively large size, A. Although several other Alouatta species are endangered, A. However, red howlers have become rarer in some areas, most likely due to the destruction of their habitat. Fortunately, they are still adundant in Brazil Nowak, Red howlers have an amusing reaction to rainy days during the tropical wet season.

In response to heavy rains, they howl, either at the onset, or often at the sound of approaching rain, and sit hunched over until the rain ends Clutton-Brock, !

Red howler monkeys have overcome problems that are usually associated with having leaves as a principle food source, including their specialized jaw and stomach structures. Behaviorally, they along with the other species in their genus are unique in that they have developed the loudest vocalization of any animal in the New World.

These adaptations have aided them in becoming an extremely successful primate--and yet they are still able to sleep for more than 15 hours a day! Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a now extinct synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds. Iteroparous animals must, by definition, survive over multiple seasons or periodic condition changes.

Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal. Clutton-Brock, T. Primate Ecology. Academic Press, NY. DeVore, I. Primate Behavior. Hausfater, G.

Aldine Publishing Co. MacDonald, D. The Encyclopedia of Mammals. Facts on File Publications, NY. Nowak, R. Walker's Mammals of the World. Johns Hopkins Univ. Press, MD. Smuts, B. Primate Societies. Help us improve the site by taking our survey. To cite this page: Normile, R. Disclaimer: The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe.

Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control. Alouatta seniculus red howler monkey Facebook.

Geographic Range Alouatta seniculus have the widest geographical distribution of all the New World primates. Biogeographic Regions neotropical native Habitat Terrestrial Biomes forest rainforest Physical Description Alouatta seniculus are slightly sexually dimorphic.

MacDonald, Nowak, Other Physical Features endothermic bilateral symmetry Range mass 4. Mating System polygynous Alouatta seniculus appears to breed throughout the year. MacDonald, Nowak, Smuts et. Conservation Status Although several other Alouatta species are endangered, A. Contributors Rebecca V. Normile author , University of Michigan-Ann Arbor. Glossary Neotropical living in the southern part of the New World.

In other words, Central and South America. Read more Connect with us Help us improve the site by taking our survey. Facebook Twitter Pinterest. Classification Kingdom Animalia animals Animalia: information 1 Animalia: pictures Animalia: specimens Animalia: sounds Animalia: maps


Venezuelan red howler

The color of both males and females is a deep reddish-brown, and the color shade changes with age. The jawbone of the red howler monkey is large, especially the body of the mandible. The position of the foramen magnum is very posterior to make way for the expanded jaw and enlarged hyoid bone. Howler monkeys also have an inflated bulla, which is the bony encasement of the middle ear. This makes them an exception among other New World monkeys. The diurnal Alouatta seniculus is an arboreal primate, so it spends much of its time high in the canopy. Its preferred method of locomotion is quadrupedal walking with minimal leaping.


Adaptive Radiations of Neotropical Primates pp Cite as. No consensus yet exists to explain the diversity of primate social organization. Although ecological and social factors are both involved in the evolution and expression of social organization, they do not necessarily act together and may differ for the two sexes Wrangham, Differing social factors usually are rooted in a species mating system— the degree of monopolization of mates by each sex—resulting from the effects of local ecology on the dispersion of the sex investing more in the production of offspring Emlen and Oring, ; Vehrencamp and Bradbury, However, some features of primate social organization are phylogenetically conservative and resist change in response to varying ecological situations Di Fiore and Rendall, At any given point in time, the particular social organization exhibited by a population also reflects recent demographic events Altmann and Altmann, ; Dunbar,

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