The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Comparison of the nutritional composition of foods consumed by howler monkeys (Alouatta pigra and A. caraya) in Mexico and Argentina


1Department of Anthropology, University of Illinois at Urbana-Champaign, 2Estación Biológica Corrientes, Museo Argentino de Cs. Naturales “Bernardino Rivadavia” (CONICET), Argentina, 3Department of Anthropology, Hunter College of the City University of New York, 4New York Consortium in Evolutionary Primatology, (NYCEP)

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Despite evidence of flexibility in the amount of monthly feeding time devoted to exploiting leaves, fruits, and flowers by howler monkeys, few studies compare inter-specific differences in howler feeding ecology in relation to nutrient concentrations of plant species and items consumed. We present data on the nutritional ecology of Alouatta pigra in Campeche, Mexico and A. caraya in Corrientes, Argentina. We conducted full-day focal follows of adult individuals belonging to two A. pigra and two A. caraya groups during 12 and 8 months, totaling 2,675 focal hours. We analyzed the nutrient content of 119 (A. pigra) and 143 (A. caraya) samples from feeding trees belonging to 32 and 26 species, respectively. While there are overall similarities in the nutrient composition patterns of the diets when considering general categories (i.e. leaves, fruits, flowers), foods consumed by A. pigra were more fibrous than those eaten by A. caraya (12-74.5% vs. 8-67.8% neutral detergent fiber [NDF]) and lower in crude [CP] and available protein [AP] (2.8-35.6% vs. 3.8-45.5% CP and 0.1-30% vs. 2-42.9% AP). Moreover, the protein-to-fiber ratios (AP:ADF) of both mature and young leaves differed (Mann-Whitney, p<0.05) between the two primate species (young leaves: 0.44±0.3 A. pigra vs. 0.82±0.5 A. caraya). The highest average AP content (15±6.9%) was found in inflorescences eaten by A. pigra, but for A. caraya it was young leaves that contained the most AP (20.7±7.3%). Our results highlight the importance of detailed nutritional information in comparisons of the feeding ecology of different primate species across their distribution.

Funding provided by NSF BCS 0922709, NSF-DDIG BCS 1128821, University of Illinois at Urbana-Champaign, IPS Research Grant, Sigma-Xi Grants-in-Aid of Research, Martha J. Galante Award, CONICET, Latin American Student Field Research Award

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