Table of Contents
Overview
Distribution
Range Description
In Colombia, A. seniculus is absent from the Pacific and the desert of the Guajira Peninsula, and has not been reported in from the Department of Nariño (Hernández-Camacho and Cooper 1976; Defler 2004). Otherwise, it is present throughout the country, except in non-forested areas and mountainous regions above about 3,000 m above sea level (though it has been reported at 3,200 m in the Central Andes) (Hernández-Camacho and Cooper 1976). In Venezuela, Bodini and Pérez-Hernández (1987) indicate that the howler monkey north of the Rio Orinoco and west through Apure basin north of the Rio Meta the is a distinct, as yet undescribed, form, but Linares (1998) labeled it as A. arctoidea, otherwise also occurring along the north coast of Venezuela. Alouatta seniculus occurs west of the Sierra de Merida and aorund Lake Maracaibo.
In summary, Alouatta juara-seniculus occurs west of the of the rios Juruá and Envira through the Peruvian Amazon north (say) of the Rio Inuya, north along the Andean Cordillera into Ecuador and in Colombia including the Cordillera Central and the Cordillera Oriental into Venezuela around Lake Maracaibo, west of the Serra de Merida. It is possible that either an undescribed red howler (Bodini and Pérez-Hernández 1987) or A. arctoidea (Linares 1998) occurs north of the Rio Meta in Colombia.
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Geographic Range
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.
Biogeographic Regions: neotropical (Native )
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Physical Description
Morphology
Physical Description
Alouatta seniculus are slightly sexually dimorphic. Females have a body length of 46-57 centimeters; males, which are larger, have a body length of 49-72 cm. Both sexes have a long, prehensile tail of approximately 49-75 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.
(MacDonald, 1985) (Nowak, 1991).
Range mass: 4.5 to 6.5 kg.
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Ecology
Habitat
Habitat and Ecology
The howler monkeys are the large leaf-eaters of the South American primate communities. The molar teeth are particularly adapted for their chewing leaves through shearing. They spend up to 70% of their day lying and sitting about quietly among the branches, fermenting leaves in their enlarged caecums. Like the spider monkeys, they are prehensile-tailed, with a naked patch of skin on the under surface at the tip. Their most characteristic feature is the deep jaw which surrounds the enlarged larynx and hyoid apparatus, a resonating chamber. It is with this enlarged and highly specialized voice box that they produce their howls (grunts, roars and barks). Howling sessions, usually involving the entire group, can be heard particularly in the early morning and are audible at distances of 1-2 kms (Drubbel and Gautier 1993).
Red howler groups are usually small, ranging in size from 2-16 animals and averaging 4-10 (Neville et al. 1988). They can have as many as 14 or 15 individuals, but they usually number four or five or up to 11 or so individuals. Group sizes recorded by Mendes Pontes (1999) on the Island of Maracá, Roraima, were generally small (from 1-5). Soini (192) observed group sizes ranging from 3-8 (mean 5.54±1.59, n=74) in the Pacaya Samiria National Reserve, Peru. Adult males will often be solitary. In red howlers, there is usually only one dominant male in the group (occasionally two), others being sub-adults, or juveniles, along with a harem of two to five females. Unlike the spider monkeys, and related to the large proportion of leaves in the diet (up to 50% of the annual diet), the howler monkeys generally have quite small and broadly overlapping home ranges, of 5 ha up to 45 ha, depending on the type of habitat (Neville et al. 1988). Gaulin and Gaulin (1982) recorded a home range of 22 ha for a group of nine howlers in cloud forest at 2,300 m. In the llanos of northern Venezuela, home ranges of A. arctoidea can be as small as 4 ha (Sekulic 1982). Two groups studied by Soini (1992) used 6 and 9 ha each in the Pacaya Samiria National Reserve, Peru.
Howlers are the only New World primates which regularly include mature leaves in their diet, although softer, less fibrous, young leaves are preferred when they are available. Their folivory and ability to eat mature leaves is undoubtedly one of the keys to their wide distribution and the wide variety of vegetation types they inhabit. Mature fruit is the other important food item, especially wild figs (Ficus) in many regions, but they also eat leaf petioles, buds, flowers (sometimes seasonally very important), seeds, moss, stems and twigs, and termitaria. Alouatta seniculus has also been seen to eat and lick clay at so-called “salado” sites in the Colombian Amazon (Izawa 1975). The reason for this and the consumption of soil from termitaria is still not clearly understood, but may involve the need for certain minerals, or may be due to the properties of clay which, by adsorption, can reduce the effects of toxins ingested with leaves.
Infant Alouatta are probably born throughout the year in Suriname, but data are not yet sufficient to determine if there is a birth peak. Crockett and Rudran (1987a,b) examined seasonal variation in births in red howlers from northern Venezuela, and found that they were less frequent during the early wet season (weaning would occur at the time of greatest food shortage). The llanos forests are more seasonal, however, than in the Guianas, and it is possible that this is not the case elsewhere. Oestrus lasts 2-4 days, with intervals between oestrous periods of about 17 days. Interbirth intervals are generally about 16.6 months, although they may be shortened by the death of an infant to about 10.5 months (Crockett and Sekulic 1984). Mean gestation length is 191 days (range 186-194, n=6) (as for A. seniculus seniculus in Crockett and Sekulic [1982], considered here to be A. arctoidea).
Size:
As for Alouatta seniculus, Venezuela
Adult male 6.31 kg (n=64), adult female 4.67 kg (n=46) (Rodríguez and Boher 1988)
Adult male weight 5.4-9.0 kg (mean 7.2 kg, n=61), adult female weight 4.2-7.0 kg (mean 5.6 kg, n=61) (Ford and Davis 1992).
Systems
- Terrestrial
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Habitat
Terrestrial Biomes: forest ; rainforest
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Trophic Strategy
Food Habits
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, 1965) (MacDonald, 1985).
Plant Foods: leaves; fruit; flowers
Primary Diet: herbivore (Folivore )
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Life History and Behavior
Life Expectancy
Lifespan/Longevity
Average lifespan
Status: wild: 25.0 years.
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Lifespan, longevity, and ageing
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Reproduction
Reproduction
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. Unfortunately for the female, this is not particulaly successful; less than 25% of offspring survive a male howler invasion.
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.
Mating System: polygynous
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 16-20 days, with the female being receptive for 2-4 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.
(MacDonald, 1985) (Nowak, 1991) (Smuts et. al, 1986)
Breeding season: Red howler monkeys breed year round
Average age at sexual or reproductive maturity (female): 5 years.
Average age at sexual or reproductive maturity (male): 7 years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average birth mass: 263 g.
Average gestation period: 190 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (female)
Sex: female: 1475 days.
Newborn A. seniculus are at first quite helpless and are carried around at the mother's belly. 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!
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female); extended period of juvenile learning
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Molecular Biology and Genetics
Molecular Biology
Statistics of barcoding coverage: Alouatta seniculus
Public Records: 0
Species: 1
Species With Barcodes: 1
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Conservation
Conservation Status
IUCN Red List Assessment
Red List Category
Red List Criteria
Version
Year Assessed
Assessor/s
Reviewer/s
Contributor/s
Justification
History
- 2003Least Concern(IUCN 2003)
- 1996Lower Risk/least concern(Baillie and Groombridge 1996)
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Conservation Status
Although several other Alouatta species are endangered, A. seniculus has no special conservation status. 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, 1991).
IUCN Red List of Threatened Species: least concern
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Trends
Population
Crude densities of 15 individuals/km² have been recorded in Colombia (Defler 2003). Soini (192) estimated an ecological density of 36 individuals/km² in the Pacaya Samiria National Reserve, Peru. In Brazil, Mendes Pontes (1999) recorded densities of 1.2-2.1 individuals/km² on the Island of Maracá, Roraima, lower in fact those for Ateles belzebuth at 5.0-5.8 individuals/km².
Population Trend
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Threats
Threats
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Management
Conservation Actions
Colombia
Amacayacu Natural National Park (293,000 ha) (Defler 1994)
Cahuinarí Natural National Park (575,500 ha) (Defler 1994)
Serrania de Chiribiquete Natural National Park (1,280,000 ha) (Defler 1994)
Cordillera de los Picachos Natural National Park (286,600 ha) (Defler 1994)
Cueva de los Guacharos Natural National Park (9,000 ha) (Defler 1994)
El Tuparro Natural National Park (548,000 ha) (Defler 1994)
Tayrona Natural National Park (15,000 ha [12,000 ha on land]) (Defler 1994)
Isla de Salamanca Natural National Park (21,000 ha) (Defler 1994)
Paramillo Natural National Park (460,000 ha) (Defler 1994)
El Cocuy Natural National Park (158,125 ha) (Defler 1994)
Sierra Nevada de Santa Marta Natural National Park (383,000 ha) (Defler 1994)
Tamá Natural National Park (48,000 ha) (Defler 1994)
Pisba Natural National Park (45,000 ha) (Defler 1994)
Los Nevados Natural National Park (58,300 ha) (Defler 1994)
Chingaza Natural National Park (50,374 ha) (Defler 1994)
Sumapaz Natural National Park (154,000 ha) (Defler 1994)
Las Hermosas Natural National Park (150,000 ha) (Defler 1994)
Los Farallones Natural National Park (150,000 ha) (Defler 1994)
Serrania de la Macarena Natural National Park (630,000 ha) (Defler 1994)
Puracé Natural National Park (83,000 ha) (Defler 1994)
La Paya Natural National Park (442,000 ha) (Defler 1994)
Tinigua Natural National Park (201,875 ha) (Defler 1994)
Nukak Natural National Reserve (855,000 ha) (Defler 1994)
Catatumbo-Bari Natural National Reserve (158,125 ha) (Defler 1994)
Ecuador
Yasuní National Park (982,300 ha) (Tirira 2007)
Sangay National Park (517,765 ha) (Tirira 2007)
Sumaco-Napo Galeras National Park (205,249 ha) (Tirira 2007)
Podocarpus National Park (146,280 ha) (Tirira 2007)
Cayambe-Coca Ecological Reserve (403,103 ha) (Tirira 2007)
Cofán-Bermejo Ecological Reserve (55,451 ha) (Tirira 2007)
Cuyabeno Faunal Production Reserve (Tirira 2007)
Peru
Pacaya Samiria National Reserve (Soini 1992)
Venezuela
Perija National Park (295,288 ha) (Venezuela, INPARQUES, 1982).
It is listed on Appendix II of CITES .
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Positive
Due to their relatively large size, A. seniculus, along with other howler species, are hunted for food and are subject to commercial export (Nowak, 1991).
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Wikipedia
Venezuelan red howler
The Red howler (Alouatta seniculus) is a South American species of howler monkey, a type of New World monkey. It is found in the western Amazon Basin in Venezuela, Colombia, Ecuador, Peru, Bolivia and Brazil. The population in the Santa Cruz Department in Bolivia was split off as a separate species, the Bolivian red howler, in 1985, and more recently it has been recommended splitting off the population in north-eastern South America and Trinidad as the Guyanan red howler.[3] All howler monkeys belong to the family Atelidae and the infraorder Platyrrhini (New World monkeys).
Contents |
Description
There is little sexual dimorphism. The males range from 49–72 cm and females from 46–57 cm long.[4] The males weigh between 5.4-9 kg, while females are 4.2–7 kg.[4] It has a long prehensile tail of approximately 49–75 cm.[4] The tail is covered with fur except for the last third underside of the tail, which allows it to grab branches. The color of both males and females is a deep reddish-brown, and the color shade changes with age.[4] Their faces are surrounded by fur and they have stubby noses.
The jawbone of the red howler monkey is large, especially the body of the mandible. The position of the foramen magnum is very posterior in the howler monkey, making way for the expanded jaw and enflated 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.
Alouatta seniculus is an arboreal and diurnal primate that spends much of its time up high in the canopy. Its preferred method of locomotion is quadrupedal walking with minimal leaping. Their long, prehensile tails also assist them with this by providing both support and grasping abilities. In addition, their hands and feet have a grasping pattern that allows them to better move about in the trees. This can be seen in their hands by the wide separation of the second and third digits.
Social interactions
It lives in groups of 3 to 9 individuals (usually 5 to 7).[5] The groups are polygynous with only one or two males and the rest females and their offspring.[4] One male is the usually dominant monkey of the group, and he is responsible for leading them to new food sites and defending them. The females of the group are in charge of the offspring. Venezuelan red howlers are most active in the morning; this is when the group is on the move to find another feeding spot. The howlers are famous for their “dawn chorus”. These sounds are roaring and howling calls that are performed mostly by the males in the group. The roars can be heard up to 5 km away in the forest, and makes their presence known in the area.[4] This is also used to prevent confrontations between groups, which will prevent energy loss by avoiding physical fighting. Because of their low-sugar diets, conservation of energy is key to their day. The calls also help in the scattering of the groups and lessens the competition over food.[4]
Diet and dentition
Howler monkeys are folivores which means that their diet mainly consists of leaves, but they also rely on nuts, small animals, fruits, seeds, and flowers for important sources of nutrition. These foods provide sugar necessary for growth and energy for the monkeys. The most important part of their diet are leaves, which they can’t live without for more than a week. They eat both older and younger leaves; however, the older leaves provide more nutrition. The howler monkeys are able to eat their largely leafy diet of fibrous leaves due to the structural aspects of their dentition. Narrow incisors aid in the ingestion of the leaves, and molars with sharp, shearing crests help them to better chew their food. In addition, they have a complex stomach that aids in the digestive process. Their hindgut and large intestine also help with digestion.[4] The hindgut contains bacteria that digest leaves and makes up a third of the Venezuelan Red Howler’s total body volume.[4]
Like other New World monkeys, the Venezuelan red howler's dental formula (maxilla and mandible) is as follows: 2 Incisors, 1 Canine, 3 Premolars, 3 Molars.
Reproduction
There is fierce sexual competition between males due to an unbalanced sex ratio.[4] The females attract males by moving their tongue around in order to initiate mating. If the male does not respond, she moves on to another mate.[4] The average gestation period is 190 days.[4] The infant will stay with the mother for 18–24 months. After males reach sexual maturity they are expelled from their natal group.[4] The male must then invade a foreign group. There, the male kills off the other leader and whatever offspring the first leader generated. By doing this, the male is killing any possible competition. Less than 25% of offspring survive male invasions.[4]
Subspecies
There are traditionally three subspecies of this howler,[3] though Stanyon et al. (1995) concluded that the number of chromosomal differences between A. s. sara and A. s. arctoidea (which resulted in A. s. sara being a considered a full species) was on a similar scale to that found between A. s. sara and A. s. seniculus by Minezawa et al. (1986).[2]
- Colombian red howler, Alouatta seniculus seniculus
- Ursine howler, Alouatta seniculus arctoidea
- Juruá red howler, Alouatta seniculus juara
References
 | Wikispecies has information related to: Venezuelan Red Howler |
 | Wikimedia Commons has media related to: Alouatta seniculus |
- ^ Groves, C. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 150. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100388.
- ^ a b Boubli, J.-P., Di Fiore, A., Rylands, A. B. & Mittermeier, R. A. (2008). "Alouatta seniculus". IUCN Red List of Threatened Species. Version 2011.2. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/43929. Retrieved 19 January 2012.
- ^ a b Groves, C. (2005). Wilson, D. E.; Reeder, D. M. eds. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 150. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100388.
- ^ a b c d e f g h i j k l m n Normile, R. V. (2001). "Alouatta seniculus information". Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/information/Alouatta_seniculus.html. Retrieved 2008-07-30.
- ^ Louise Emmons and Francois Feer (1997). Neotropical Rainforest Mammals.
- Heatwole, Alan M.. Monkeys and Apes. 1st. New York: Gallery Books, 1990.
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