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Alouatta palliata


Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Atelidae
Subfamily: Alouattinae
Genus: Alouatta
Species: A. palliata
Distinction: The Mantled Howler looks very similar to other Howler monkeys however, the Mantled Howler has gold or light brown guard hairs on each side.
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Range and Abundance: Mantled Howlers can be found throughout Central American from Mexico to Colombia. Howlers can live in secondary & semi-deciduous forests but are found more often in older evergreen forests. While Howlers are considered to be "of least concern" by the IUCN they are still affected by fragmentation of the Rain forests. Howlers are seen to have an advantage over other rain forest organisms because their biology allows them to have a widely varied diet.
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Coloration and Morphology: Mantled Howlers are primarily black, aside from the guard hairs. Females grow to be between 18 and 25 inches and males are usually 20 to 27 inches. Howlers have a prehensile tail that is very useful for grasping or holding of tree branches. There is a great difference in weight among different populations, females can range between 6 to 17lbs. and males from 10 to 22 lbs. The Alouatta palliata is the largest of the New World Monkeys. Aside from being generally larger, males have longer facial beards than females and upon sexual maturity the scrotum turns white. Juvenile Howlers range from golden-brown to a silvery color.
Habitat: Howlers can be found in all levels of the Rain forest Canopy but are most often found in the upper third. They live in forests with elevations from 0 to 2000 meters.
Diet: Alouatta palliata is a herbivorous Monkey, the majority of its diet consists of leaves, particularly ficus leaves. During the dry season they consume a great deal of fruit: figs and sometimes maggots. Because of their low-energy diet Howlers often rest horizontally on branches throughout the day and night



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Predators: Predators include large birds of prey such as the Harpy Eagle (most threatening to the young), tree-dwelling snakes have also been known to threaten Howler Monkeys.


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Competitors: While Howler Monkeys have a generally easy lifestyle- spending most of the day resting they compete for resources mostly with other monkeys such as the White-faced Capuchin.





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Behavior: Mantled Howlers live in groups of 20-30 members, before reaching sexual maturity offspring are exiled from the group (this helps to expand the gene pool). These groups are polygamous with an alpha male who has dominance in mating and eating, younger animals generally have a higher status than the older individuals. Groups generally do not travel far (between 10 and 60 hectares) and when confronted with another species will fight but generally they ignore each other.
Communication: Particularly between dawn and dusk (also in response to predators) male Howlers can be heard grunting and roaring. This is possible because Howlers have a hyoid bone, a small hollow bone near the vocal chords that amplifies the sound. Females can also produce call sounds but they are often of a higher pitch and lower volume. Howlers also communicate with one another via urine rubbing and often communicate with humans by urinating or defecating on them.
Costa Rica Experience: While on a River tour, a large group of monkeys was discovered in a group of trees very close to the shore. As our group approached their location the Monkeys began howling and the group began rapidly moving. Despite the fact that the group of humans was there to study the Alouatta, they seemed to be studying us- the group congregated in 2-3 trees in which many of the members lied down and kept a very close eye on their invaders. After we had been observing the group for quite some time I had the chance to see the Alpha male who was massive in comparison- he must not have seen us as any kind of a threat because although he was quite vocal, he remained in the background. I was also able to see first-hand their use of prehensile tails- they attach the tail like a safety line to a branch and do not release it until they are comfortably on another branch; they can use the tail as a fifth limb to grab onto anything when jumping from tree to tree.


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Citations:


The Basal Metabolism of Mantled Howler Monkeys (Alouatta palliata)- Katharine Milton, Timothy M. Casey and Kathleen K. Casey, Journal of Mammalogy, Vol. 60, No. 2 (May, 1979), pp. 373-376
Population Density of the Mantled Howler Monkey (Alouatta palliata) at La Selva Biological Reserve, Costa Rica: A New Technique to Analyze Census Data - Kathryn Elizabeth Stoner, Biotropica, Vol. 26, No. 3 (Sep., 1994), pp. 332-340
Some Parasites of the Howler Monkey of Northern Argentina - Betty Locker Pope, The Journal of Parasitology, Vol. 52, No. 1 (Feb., 1966), pp. 166-168
Factors Influencing Leaf Choice by Howler Monkeys: A Test of Some Hypotheses of Food Selection by Generalist Herbivores- Katherine Milton Am Nat 1979. Vol. 114, pp. 362
IUCN Red List (January, 2009)- http://www.iucnredlist.org
Broekma, I. (2002) Natural History of the Mantled Howler Monkey (Alouatta palliata) Primates of Panama (March, 2004)- http://www.primatesofpanama.org/academicresources/articles/howler.htm
Animal Diversity Web – Mantled howler monkey (March, 2004)- http://animaldiversity.ummz.umich.edu/site/accounts/information/Alouatta_palliata.html
Primate Behaviour – Mantled howler monkey (March, 2004)- http://members.tripod.com/uakari/alouatta_palliata.htm