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Session 8: The Atelines

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Author: Agustin Fuentes
Ecology, behavior, and conservation of the Atelines.

1.  Key Concepts:

The Atelines are the largest of the New World primates.  Often referred to as New World apes, the Atelines are in parallel convergence with apes.

2.  Terms & Definitions:

Frugivorous
Fruit-eating
Insectivorous
Insect-eating
Prehensiled
Possessing the ability to use an appendage as an additional "hand" and is often used in relation to tails.

3.  Ateline Taxonomy:

The Atelines are comprised of four genera, with a distribution throughout Central and South America.  The historical range extends into the Caribbean, but the current range is reduced.  Additionally, there is no evidence of human co-occurrence until recently.  The genera of the Atelines and their distributions:

  • Alouatta, or the howler monkeys: Central and South America.
  • Ateles, or the spider monkeys: Central and South America.
  • Brachyteles, or the muriquis: Atlantic Forest Brazil.
  • Lagothrix, or the woolly monkeys: Northeastern South America.

4.  Ecology and Reproductive Strategies:

One of the most remarkable characteristics of the atelines is the diversity of grouping patterns and social systems represented in the taxa.

Ecology:

The Atelines are generally frugivorous, but Alouatta and Brachyteles can be heavily folivorous and Lagothrix can also be heavily insectiviorous.  Often, groups form smaller fission/fusion groups specifically for feeding.  The Atelines are exclusively arboreal and possess strong prehensiled tails. Brachyteles and Ateles use rapid suspensory, semi-brachiating locomotion (w/ morphological adaptations).

Grouping patterns:

Grouping patterns vary by genera and species.  Alouatta tends to be the most distinct, forming many one male/ mutli-female groups, with some male dispersal occurring.  Generally, grouping patterns tend to be:

  • Multi-female/ multi-male
  • Female dispersal in general
  • Fission-fusion grouping patterns in Ateles and Brachyteles

Behavior:

Female-female competition is common, and female-female aggression is the most common type of aggression documented.  Male infanticide is not uncommon, especially in the red howler monkey.  Brachyteles males exhibit extremely low levels of overt aggression and almost never participate in fighting.  In Brachyteles and Lagothrix, no grooming occurs.  IVocalization and spatial proximity is important in lieu of grooming.  Kin groups and dominance relations are extremely important in Ateles and Lagothrix.

5.  Conservation and Predation:

Humans are the largest predators of the Atelines.  They are the largest mammals in the trees.  Ateline populations have suffered drastic population losses with corresponding increases in human populations.  Howler monkeys are currently the only group responding well to conservation efforts.

6.  Additional Material:

Required Reading:

Primates in Perspective.  2007.  C. J. Campbell. A. Fuentes. K.C. MacKinnon. M. Panger. S.K. Bearder.  Oxford University Press.

Chapter 10: The Atelines: Variation in Ecology, Behavior, and Social Organization - DiFiore & Campbell.

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