Alouatta caraya
Black Howler Monkey
Courtesy of Honolulu Zoo
http://www.honoluluzoo.org (The webmaster asked that a linked be included)
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. Tongueflicking 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 the northeastern 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 7-25-05.