Alouatta caraya - Black Howler Monkey
Courtesy of Honolulu Zoo
Physical Description:
Adult black howler monkeys are
sexually dimorphic. Males have a black
pelage and females a tan pelage. At
birth, both sexes have yellow to reddish pelage which they retain until they
reach 54 months (Redford and Eisenberg 1992).
Males weigh 6.5 kg and females 4.5kg (Robinson and Redford 1986, Redford
and Eisenberg 1992). The lower mandibles
and hyoid bone are enlarged to form a resonate chamber, which is covered by
their large beard (Mowes et al. 1989). They have a strong prehensile tail, which
lacks hair on the underside. Tail length
is 53.1-65 centimeters. The dental formula for Alouatta caraya is 2/2-1/1-3/3-3/3 = 36. Alouatta is the only genus of platyrrhine
with trichromatic color vision (Jacobs et al. 1996).
Distribution:
Alouatta caraya is
found in southern Brazil, western Paraguay and the Pilcomayo
River region, Bolivia, and the Salta, Chaco, Formosa,
Santa Fe and Misones provinces of northern Argentina. Specifically they are found in the xeric
regions of the Chaco and in forested areas along the Paraguay
and Pilcomayo rivers.
Robinson and Redford (1986) found Alouatta caraya at a density of 42.2/km2. Density is a function of body size.
(courtesy of: http://hoglezoo.org/animals/view.php?id=144)
Ontogeny and
Reproduction:
The average gestation period for Alouatta caraya is 187
days. They give birth to a single offspring,
which weighs 113 grams (Redford and Eisenberg 1992). Parturition occurs during the dry season; August
through October. The mammaries are laterally-proximal to the axillary region. Alloparental care is common among adults and juvenile
females. Bravo and Sallenave
(2002) observed adoption on one occasion.
Black howler monkeys have a unique chromosome type of X1X2Y1Y2 (Mudry et al. 1998). The
average life span is 16 years but they can live up to 20 years in
captivity.
Ecology and Behavior:
Alouatta caraya are diurnal and live in single-
and multi-male groups (Crockett and Eisenberg 1987). Zunino et al.
(2001) observed that as density, or troop size, increased, the sex ratio
remained the same. Redford and Eisenberg
(1992) estimated average troop size at seven black howlers. The largest male in the troop is the dominant
member.
Alouatta caraya
primarily lives in the upper and middle strata of the forest canopy, but they
can be found at all levels in some habitats. The activity budget of Alouatta caraya is
56.5% rest, 18.9% feeding, 10.5% travel, 2% confrontations, 6% general
movement, and 6% social interactions.
Social interactions are a mixture of allogroming
and play. Play occurs at all age levels
and is the most significant of all social interactions (Bravo and Sallenave 2002). Mating
always occurs within the troop.
Tongue-flicking is a behavior commonly associated with mating.
The monkeys are territorial and
commonly use scent marking to set boundaries.
Home range size is 1.7-2.2 hectares and 76-82% of that area is actively
defended through vocalization and confrontation (Bravo and Sallenave
2002). High density promotes a smaller
home range size. If energy is not
limited, activity levels will increase, as will the probability of
confrontations as howlers expand into the distal portions of their home ranges
(Bravo and Sallenave 2002).
Alouatta caraya are folivorous-frugivorous
and are able to break down the tannins in leaves with their large salivary
glands (Milton 1987, Bravo and Sallenave, 2002). Their diet depends on mature leaves in July
and shifts to mature fruits by November. There is a direct association between
the density of howlers and density of fruiting trees (Zubino
et al. 2001). They obtain water through leaves.
Black howlers have been observed "drinking" by licking their
hands when succulent leaves are not available.
Remarks:
T.
callithricis is a parasite found to infect 9.8%
of black howler monkeys (Prieto et al. 2002).
Black howlers are listed as a Cites Appendix II species.
Literature Cited:
Bravo, S. P. and A.
Sallenave. 2002.
Foraging behavior and activity patterns
of Alouatta caraya in thenortheastern Argentinean flooded forest. International Journal of Primatology 24(4):825-845.
Crocket, C. M. and J. F. Eineberg.
1987. Howlers: variation in group size and
demography. In Smuts, B. B., D. L. Cheney, R. M. Seyfarth,
R. W. Wrangham and T. T. Struhsaker
(eds.) Primate Societies. University of Chicago Press, Chicago IL. pp. 54-68.
Jacobs, G. H., M. Nietz, J. F. Deegan, J. Neit and D. Neit. 1996. Tricromatic colour vision in new world monkeys. Nature (382):156-158.
Milton, K. 1987. Physiological characteristics of the genus Alouatta. International Journal of Primatology
8:428.
Mowes, M. A., R.
A. Ojedoi and R. M. Berquez. 1989.
Guide to Mammals of Salta Province, Argentina.
Mudry, M. D., M.
Rahn, M. Gorostiaga, A. Hick,
M. S. Merani and A. J. Solari. 1998. Revised
karyotype of Alouatta caraya (Primates: Platyrrhini)
based on synaptonemal complex and banding analyses. PubMed 128(1):9-16.
Prieto, O. H., A. M. Santa Cruz,
N. Scheibler, J. T. Borda and
L. G. Gómez. 2002. Incidence and external morphology of the nematode
Trypanoxyuris (Hapaloxyuris) callithricis, isolated from black-and-gold howler monkeys
(Alouatta caraya) in Corrientes, Argentina. Laboratory Primate Newsletter 41:3.
Redford, K. H. and J. F. Eisenberg. 1992.
Mammals of the Neotropoics: the southern core,
Volume 2. University of Chicago Press, Chicago.
Robinson, J. G. and K. H. Redford. 1986.
Body size, diet and population of neotropical
mammals. The American Midland Naturalist
128(5):665-680.
Zunino, G. E., V. Gonzalez, M. M. Kowalewski and
S. P. Bravo. 2001. Alouatta caraya relations among habitat density and social
organization. Primate Report 61: 37-45.
Reference written by
Michael Uffenbeck, Biol 378
(Mammalogy), University of Wisconsin – Stevens
Point: Edited by Chris Yahnke. Page last updated July
25, 2005.
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