Feeding ecology of olive baboons in the Kibale forest: Preliminary results on diet and food selection June 5 th July 11 th Caley Johnson

Transcription

1 Feeding ecology of olive baboons in the Kibale forest: Preliminary results on diet and food selection June 5 th July 11 th Caley Johnson Male baboon feeding in Kibale National Park, Uganda What do forest baboons eat? A number of feeding and basic nutritional studies have been done on baboon (Papio) species. 1,2 Most research on olive baboons (Papio anubis), however, has focused on populations living in the savannah, with comparatively little research on those in forested habitat. 3 In a preliminary study, we report results of diet composition and feeding behavior in a group of forest living olive baboons in Kibale National Park, Uganda. Additionally, we assess the nutritional objectives of this group by comparing the nutrient content of foods eaten and parts rejected in food preparation to determine the nutritional aspects of food selection. 2 Fig. 1 Study Area

2 METHODS This study was conducted at the Kanyawara site in Kibale National Park, Uganda ( N and E) from July 2009 to July 2011 (Fig. 1). A single group of baboons was followed for at least three consecutive days per month by CAJ and field assistants as part of the habituation process. When it was possible to observe baboons feeding, we documented feeding events by identifying and recording food items. In July 2010 the group was followed for two consecutive weeks while food items and plant parts discarded in food preparation were collected on the same day they were processed for nutritional analysis. Samples were measured for neutral and acid detergent fiber 4, lignin 4, crude and available protein 4, nonstructural carbohydrates 4, digestible energy 5, condensed tannins 4, and hydrolyzable tannins 6 using established methods. Paired eaten and discarded parts were compared for their macronutrient and tannin content by performing paired Wilcoxon signed rank tests. Mann-Whitney tests were performed to compare the overall differences in macronutrient and tannin content in all eaten vs. discarded foods. Olive baboons feeding in Kibale National Park, Uganda

3 Caley Johnson and colleagues preparing baboon food samples in the field RESULTS 190 feeding events were recorded during which baboons were observed to feed on 32 plant species and 10 plant parts (see Fig. 2 for diet composition). 21 samples from 12 species were collected and analyzed for macronutrients and tannins (9 items consumed and 12 discarded), representing 77% of species consumed during recorded feeding events. Foods and discards were similar in protein, energy and non-structural carbohydrates. Fat content was extremely low in all food parts (<3%). Foods eaten were lower in hemicellulose than discarded counterparts (Z = , p = 0.021). Cellulose was similar between discarded and eaten parts. Eaten foods had higher lignin than paired discards (Z = -2521, p = 0.012), but not when all eaten and discarded parts were compared (see Fig. 3). Condensed tannins were present in 10 of 12 discarded parts, but only 5 of 9 eaten parts. No foods contained hydrolyzable tannins.

4 Fig. 2 Diet Composition (other = seeds, insects, mushrooms, bark) Fig. 3 Comparison of eaten and discarded food parts (NDF=neutral detergent fiber, ADF=acid detergent fiber, TNC=total non-structural carbohydrates, * =significant difference)

5 How do forest baboons compare? Previous studies found that savannah baboons select for foods high in protein and low in fiber and tannins. 2 We found that baboons selected food parts that were lower in NDF; however, we found no difference between eaten and discarded items in most other major macronutrient groups. The baboons in this study may have shown selection against tannins, as discarded parts had a higher proportion of condensed tannins than eaten foods. Future directions for comparative study include examining the role of food availability in diet selection, and addressing underlying nutritional goals that govern nutrient intake to expose larger dietary patterns. References 1 Altmann (1998) Foraging for survival: yearling baboons in Africa, University of Chicago Press, Chicago 2 Barton, Whiten A (1994) Behavioral Ecology and Sociobiology 35: Rowell (1966) Journal of Zoology 149: Rothman, Dierenfeld ES, Molina DO, Shaw AV, Hintz AF, Pell AN (2006) American Journal of Primatology 68: Maynard (1944) Journal of Nutrition 28: Hartzfeld, Forkner, Hunter, Hagerman, Journal of Agricultural and Food Chemistry 50: Acknowledgments Scott Williams, Jenny Paltan, Aerin Jacob, Moses Musana, James Magaro, Jessica Rothman, Larissa Swedell, Whitney Reiner