International Journal of Primatology

, Volume 29, Issue 6, pp 1455–1466 | Cite as

It’s Tough Out There: Variation in the Toughness of Ingested Leaves and Feeding Behavior Among Four Colobinae in Vietnam

  • B. W. WrightEmail author
  • L. Ulibarri
  • J. O’Brien
  • B. Sadler
  • R. Prodhan
  • H. H. Covert
  • T. Nadler


Colobines are similar in their exploitation of a high percentage of leaf matter. However, this observation obfuscates interesting differences among genera of Southeast Asian colobines in morphology and behavior that may be reflected in the degree to which they rely on mastication or gut volume and gut retention time when ingesting and digesting leaves. We detail the use of a laboratory-based method to measure the mechanical properties of foods selected and processed by 4 captive species of Southeast Asian Colobinae —Pygathrix nemaeus, Pygathrix cinerea, Trachypithecus delacouri, and Trachypithecus laotum hatinhensis— at the Endangered Primate Rescue Center (EPRC), Vietnam. We also detail a field method that quantifies chewing rates and chewing behavior via a consumer-grade video camera and laptop computer. Observations in the captive setting permit a degree of experimental control that is not possible in the wild, and the location of the EPRC in the primates’ habitat country permitted us to provide leaves that they encounter and eat in the wild. We collected toughness data with a portable tester designed by Lucas et al. The average toughness of selected leaves does not differ among the taxa, nor does the length of time spent chewing foods. However, there are differences in feeding rate, with Trachypithecus spp. chewing foods twice as fast as Pygathrix spp. Our findings suggest that Trachypithecus spp. emphasize comminution of food by mastication, while Pygathrix spp. emphasize the comminution of leaf matter in the stomach. The hypothesis is supported by data on molar size, gut mass, and gut morphology. We provide new insights into dietary variation among primate species and detail methods that are typically conducted only in a laboratory setting. We augment the findings with additional data on activity, feeding rates, and tooth morphology.


chewing rates food material properties portable mechanical tester Southeast Asian colobines toughness 



We thank Mr. Truong Quang Bich, Director of Cuc Phuong National Park, and Mr. Do Van Lap, Chief of Scientific and International Collaborations. We also thank Nguyen Thi Thu Hien, Uli Streicher, Elke Schwierz, and all of the staff at the EPRC for their support, advice, and friendship. Finally, we thank Dr. Peter Lucas, Dr. Kristin Wright, and Dr. Nancy Stevens for their advice and expertise. The CU Museum’s Burt Fund, CU Anthropology Department, Zoological Society of San Diego, and the National Geographic Society provided funding for our study.


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • B. W. Wright
    • 1
    Email author
  • L. Ulibarri
    • 3
  • J. O’Brien
    • 3
  • B. Sadler
    • 2
  • R. Prodhan
    • 2
  • H. H. Covert
    • 3
  • T. Nadler
    • 4
  1. 1.Department of AnatomyKansas City University of Medicine and BiosciencesKansas CityUSA
  2. 2.Department of AnthropologyThe George Washington UniversityWashingtonUSA
  3. 3.Department of AnthropologyUniversity of ColoradoBoulderUSA
  4. 4.Endangered Primate Rescue CenterNho Quan DistrictVietnam

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