Black Howler Monkey Alouatta Pigra

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Black Howler MonkeyAlouatta Pigra
http//www.cs.mcgill.ca/dtremb8/apigra.ppt

• Stephanie Larocque
• Joseph Leung
• Daniel Tremblay-Sher
• Myriam Tremblay-Sher
• Diana Yin

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Taxonomy
Primates
Strepsirrhini
Haplorrhini
Tarsiiforms
Simiiforms
Platyrrhini
Catarrhini
Cebidae
Pitheciidae
Aotidae
Atelidae
Atelinae
Alouattinae
Alouatta
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Species Description

• Alouatta genus is defined in large part by
  characteristic howling, hence the common name
  Howler.
• Several species exist in Central America
  including
• A. belzebul, A. caraya, A. coibensis, A.
  paliatta, A. pigra, A. sara, A. seniculus.
• Until 1970, A. pigra was considered a subspecies
  of A. paliatta, but enough distinctive traits
  warrant its reclassification as a seperate
  species.

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Species DescriptionGeographical Distribution
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Species DescriptionGeographical Distribution

• Central America
• Yucatan Peninsula, Mexico
• Guatemala
• Belize
• Tropical evergreen, semi-evergreen forest
• Altitudes below 400m.
• Riverine areas with seasonal flooding

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Species DescriptionPhysical Characteristics

• Prehensile Tail
• Weight 6-8kg
• Length 60cm 80cm tail
• Coat Black fur with traces of brown on
  shoulders, cheeks, and back. Distinctive white
  scrotum by the age of 4 months.
• Upper molars have sharp shearing crests which
  aids in grinding leaves.
• Opposable thumbs and big toes.
• Large salivary glands break down tannin in leaves.

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Species DescriptionDiet

• Varied diet
• Hybrid frugivore/folivore as well as flowers.
• Composition of diet depends on season and
  availability of different foods.
• Research suggests that A. Pigra prefer fruit but
  will supplement with leaves when needed.
• Fruit abundance is highest from July to December.
• Flower abundance is highest from April to June.

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Species DescriptionDiet
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Species DescriptionActivity
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Social OrganizationGroup composition

• Small troops of 4-8 individuals
• Troop composition is usually 1-4 males, with
  numerous females and their offspring.
• Many groups featuring a single male and 1-3
  females
• Sometimes exhibit monogamous behaviour, in
  contrast to A. palliata's multiple male/female
  group composition.
• Bands of roaming bachelor males challenge the
  males of mixed groups for dominance.

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Social OrganizationTerritoriality

• A. Pigra's territory
• Depending on size of group, territory size can
  range from 2-25 acres.
• Territory provides food and living spaces.
• Is A. Pigra territorial? Certain evidence
  points to the use of howling for territorial
  defense.

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Social OrganizationReproduction

• A. Pigra reaches reproductive maturity at age 4
• Gestation period is 180 days
• Females in social group often tend to infants who
  are not their own.
• Individuals from both genders usually disperse
  from their natal groups as early as 25-30 months
  of age or as late as adulthood.
• In some cases individuals remain with their natal
  group.

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Social OrganizationMating Rituals

• Sexual Behaviour
• Following A male follows a female in estrus
  closely, often within physical reach. During
  this time the male focuses on the female often
  ignoring other individuals, social activities,
  and even eating.
• Urine Sniffing Typical male behaviour while
  following.

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Social OrganizationMating Rituals

• Sexual Behavour (cont.)?
• Male Herding A male stands closely or directly
  in front of a female, forcing her to
  recognize/acknowledge him and preventing her from
  walking towards another male
• Adulterous Breeding Documented examples of
  females from one troop mating with males from
  neighbouring troop.

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Social OrganizationCopulation
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Special Feature HowlingBackground

• Human anatomy
• the hyoid bone is suspended in the neck and is
  under the mandible bone, which is the bone
  structure at the bottom of our face. Its
  function is to support the tongue.

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Special Feature HowlingAnatomy

• In A. Pigra, the hyoid bone is enlarged, and
  resides within in an enlarged pouch beneath the
  throat, which is hidden by a thick beard.
• This cavity acts as a resonance box which
  generates lower frequencies, and amplifies the
  howl.

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Special Feature HowlingTaxonomy, Phylogeny and
Evolution

• Defining feature of Alouatta genus.
• Unique hyoid bone morphology has been used
  historically to classify species within the genus
  Alouatta in three groups
• seniculus group
• A. seniculus, A. belzebul, A. fusca
• palliata group
• A. palliata, A. pigra, A. coibensis
• caraya group
• A. caraya

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Special Feature HowlingTaxonomy, Phylogeny and
Evolution

• Molecular and phylogeny studies imply a slightly
  different grouping
• A. belzebul and A. seniculus form a clade with A.
  fusca as the sister taxon
• A. palliata is the sister taxon to the remaining
  taxa.
• Establishes A. palliata (and closely related A.
  pigra) as more primitive species within the
  genus, and A. seniculus as more evolved.

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Special Feature HowlingEvolution and
Specialization

• Further down the evolutionary tree, hyoid bone is
  more developed.
• This contributes significantly to differences in
  calls between species
• A. seniculus produces calls with frequencies
  ranging from 350 to 3500 Hz, and spectral energy
  concentration on 350-1100Hz
• A. caraya, which is more primitive, produces
  strongest calls in the more limited 310-328 Hz
  range

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Special Feature HowlingRange

• These low frequency calls carry better in dense,
  humid, tropical forest.
• Long distance call can be heard at least 1km away
• Calls often repeated by monkeys at top of trees,
  making them louder than what is heard by
  observers below canopy.
• Calls carry farthest in the morning, intermediate
  distances in the evening, and shortest midday due
  to differences in humidity.

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Special Feature HowlingInformation Content

• The frequency and volume of the call is
  influenced by the size and shape of the hyoid
  bone and the throat.
• In adult males, this cavity is larger and allows
  the individual to generate the loudest and lowest
  frequency calls.
• Therefore when listening to a chorus of howlers,
  by listening for the different frequencies, one
  can get basic information about troop size and
  composition.

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Special Feature HowlingPurpose

• Howling can be provoked by extrinsic factors
• airplanes passing
• falling trees
• rain showers
• nearing of tourists, other howlers or spider
  monkeys
• responding to human mimicry

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Special Feature HowlingBimodality and
Territoriality

• Most monkeys with long range calls exhibit a
  strong early morning peak in calling activity
• A. Pigra additionally exhibits a strong late
  afternoon peak, so its calls follow a bimodal
  distribution.
• During the rainy season, the peaks are less
  sharply defined (more calling midday) attributed
  to rain, lower sunlight.

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Special Feature HowlingBimodality and
Territoriality

• Horwich and Gebhard (1983) note
• Of all the species with long range vocalizations,
  there appears to be a correlation between those
  with bimodal calling distributions and those
  which exhibit territorial defense.
• Recorded three incidents in A. pigra of troops
  being chased across boundaries, followed by
  increased howling within 100m of the border.
• Conclusion A. Pigra exhibits signs of
  territoriality

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Special Feature HowlingTerritoriality

• Cornick and Markowitz (2002)
• No significant evidence of territoriality
• Typically large overlap of home ranges
• Folivorous species rarely territorial
• Passive lifestyle for digestion
• Leaves not usually a depletable resource
• Conclusion not territorial.
• Compromise Klein (1974) describes an active
  calling response following an incursion into a
  shifting group space surrounding the troop.

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Conservation

• Good news
• Not in immediate danger
• Cause for concern
• Increasing forest fragmentation
• Estrada shows that between 1984, and 2001, there
  was a loss of 3351 ha of rain forest vegetation.
  Most is because of humans. Converting forest land
  to open field. This change leads to a great
  increase in forest fragments.

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ConservationPrimates and Fragmentation

• In general, forest fragmentation can ...
• prevent a primate species from living in or
  traveling to different forest fragments, can
  cause localized extinction.
• alter group size, or population densities
• alter the dietary strategies of the species
• affect gene flow amount populations

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ConservationFragmentation and A. Pigra

• More good news
• According to studies by Silver and Marsh, Howler
  monkeys do much better in forest fragments
  compared to other primate species.
• In this study, 2 troops of Howler monkeys living
  on a community Baboon Sanctuary (CBS) were
  transferred, radio transmitter collars were
  placed on them, and then they were Tran located
  to the Cockscomb Basin Wildlife Sanctuary. (CBWS)?

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ConservationAdaptations

• Flexible diet
• Try novel foods very quickly, making unfamiliar
  goods readily exploitable to Howler monkeys.
• Restricted energy expenditure when food sources
  become scarce
• Avoiding moving more than necessary.
• Even in times of food abundance Howlers have been
  seen to rest a lot, perhaps as a way to maintain
  reserves in times of seasonal fluctuations.

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ConservationConclusions

• Howler monkeys appear very capable of living in
  small forest fragments. (Being able to live in
  smaller environments may make it easier to breed
  howler monkeys in zoological gardens, but further
  research is needed.)?
• Despite techniques that permit howler monkeys to
  do well in forest fragments, it is possible that
  howlers are unsafe on a long-term basis. Under
  fragment conditions they are more vulnerable to
  being hunted, disease, predation, food shortages,
  and inbreeding.

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Bibliography

• Books and Journals
• Baumgarten, A., Williamson, G.B. (2006). The
  Distribution of Howling Monkeys (Alouatta pigra
  and A.Palliata) in Southeastern Mexico and
  Central America. Primates,48, 310-315.
• Bearder, S.K., Campbell, C.J., Fuentes, A.,
  Mackinnon,C.K., Panger, M. (2007). Primates in
  Perspective. New York Oxford University Press.
• Bramblett, C.A. (1976). Patterns of Primate
  Behavior. Palo Alto, California Mayfield
  Publishing Company.
• Castellanos, L., Estrada, A., Garcia, Y.,
  Mendoza, A., Munoz, D., Pacheco, R., Van Belle,
  S. (2002). Population of the Black Howler Monkey
  (alouatta pigra) in a Fragmented Landscape in
  Palenque, Chiapas, Mexico. American Journal of
  Primatology, 58, 45-55.
• Estrada, A., Garber, P.A., Luecke, L., Pavelka,
  M. (2006). New Perspectives on the Study of
  Mesoamerican Primates  Distribution, Ecology,
  Behavior, and Conservation. New York Springer
  Science Business Media, Inc.
• Fleagle, J.G. (1988). Primate Adaptation and
  Evolution. Academic Press.
• Gonzalez-Kirchner, J.P. (1998). Group Size and
  Population Density of the Black Howler Monkey
  (alouatta pigra) in Muchukux Forest, Quintana
  Roo, Mexico Electronic version. Folia Primatol,
  69, 260-265.

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Bibliography

• Horwich, R.H., Gebhard, K. (1983). Roaring
  Rhythms in Black Howler Monkeys (alouatta pigra)
  of Belize Electronic version. Primates, 24(2),
  290-296.
• Horwich, R.H. (1983). Breeding Behaviors in the
  Black Howler Monkey (alouatta pigra) of Belize
  Electronic version. Primates, 24(2), 222-230.
• Horwich, R.H., Johnson, E.D. (1986).
  Geographical Distribution of the Black Howler
  (alouatta pigra) in central America Electronic
  version. Primates, 27(1), 53-62.
• Kinzey, W.G. (1997). Alouatta. in New World
  Primates Ecology, Evolution, and Behavior. New
  York Aldine de Gruyter.
• Marsh, L.K. (2003). Primates in Fragments
  Ecology and Conservation. New York Kluwer
  Academic/plenum publishers.
• Pavelka, M., Knopff, K.H. (2004). Diet and
  Activity in Black Howler Monkeys (Alouatta pigra)
  in Southern Belize Does Degree of Frugivory
  Influence Activity Level? Electronic Version.
  Primates, 45, 105-111.

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Bibliography

• Silver, S.C., Ostro, L.E.T., Yeager, C.P.,
  Horwich, R. (1998). Feeding Ecology of the Black
  Howler Monkey (Alouatta pigra) in Northern Belize
  Electronic Version. American Journal of
  Primatology, 45, 263-279.
• Sleeper, B. (1997). Primates The Amazing World
  of Lemurs, Monkeys, and Apes. San Francisco
  Chronicle Books.
• Strier, K.B. (2007). Primate Behavioral Ecology.
  Boston Pearson Education, Inc.
• Villalobos, F., Valerio, A.A., Retana, A.P.
  (2004). A Philogeny of Howler Monkeys (Cebidae
  Alouatta) Based on Mitochondrial, Chromosomal and
  Morphological Data Electronic Version.
  International Journal of Tropical Biology and
  Conservation, 52(3), 665-677.
• Internet Websites
• Animal Diversity Web (n.d.) Retrieved October 2,
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  te/accounts/classification/path/Alouatta.htmlAlou
  atta
• Black Howler Monkey (n.d.) Retrieved September
  15, 2007, fromhttp//www.belizezoo.org/zoo/zoo/mam
  mals/how/how1.html
• Guatemalan Howler Monkey (Alouatta Pigra) (n.d.)
  Retrieved September 25, 2007, fromhttp//www.thepr
  imata.com/alouatta_pigra.html

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Bibliography

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