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Grantee Research Project Results

Grantee Research Project Results

The Spatial and Temporal Patterns in the Deposition and Fate of Large-Seeded Species Dispersed by the Chimpanzee in the Nyungwe Forest Reserve, Rwanda

EPA Grant Number: U916183
Title: The Spatial and Temporal Patterns in the Deposition and Fate of Large-Seeded Species Dispersed by the Chimpanzee in the Nyungwe Forest Reserve, Rwanda
Investigators: Gross-Camp, Nicole D.
Institution: Antioch New England Graduate School - NH
EPA Project Officer: Graham, Karen
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $108,172
RFA: STAR Graduate Fellowships (2003)
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration



The objective of this research project is to examine the following question: What are the spatial and temporal patterns in the deposition and fate of large-seeded species dispersed by the chimpanzee in the Nyungwe Forest Reserve, Rwanda? Using the seed dispersal model developed by Schupp (1993), I will investigate the following hypotheses: chimpanzees are qualitatively effective seed dispersers of large-seeded species by (a) handling seeds in a way (i.e., swallowing and passing intact via feces) that does not destroy them and enhances germination rates; (b) depositing seeds in microsites that increase the likelihood of seed survivorship (i.e., away from the parent crown and spatially limited resources); and (c) the quality of chimpanzee seed dispersal varies because of deposition patterns into microsites that differ in rates of postdispersal seed survivorship (i.e., removal by predator or secondarily dispersed).


I will use a combination of observations and experiments to evaluate my hypotheses. To assess chimpanzee habitat use and seed deposition patterns, I will use a geographic information system (GIS) to create a map of the Nyungwe Forest indicating points of feces deposition and surrounding vegetation characteristics. Vegetation types will be scored based on various parameters (e.g., stem density, degree of canopy closure, and density of herbaceous layer) in a modified version of Lambert (1999). These data will be incorporated into a GIS layer and used to choose vegetation types for the germination experiments described below.

To evaluate the hypothesis that chimpanzees are qualitatively effective dispersers in their treatment of seeds, all seeds greater than 2 mm will be identified using a seed reference collection, counted, measured, and assessed for handling quality (i.e., destroyed or passed intact). Although the majority of seeds will be saved for use in a germination experiment, some dung piles will be returned where found and monitored for seed removal as outlined in Rogers, et al. (1998). To examine for intraspecific competition, distance measurements to the nearest adult conspecific will be recorded.

To evaluate the hypothesis that chimpanzees are qualitatively effective dispersers by their seed deposition into specific microsites, I will conduct a germination experiment. I will select three large-seeded tree species for germination experiments. Species will be selected based on reliable swallowing of fruit/seed by the chimpanzees and appearance of seed in feces (i.e., passed intact). Given the uncertainty of when a tree species will fruit, I will choose my experimental group based on the observations made during the beginning of the study.

Germination plots will be established in three different vegetation types determined by areas of regular feces deposition. If the chimpanzees use regenerating areas, I will evaluate the hypothesis that chimpanzees introduce seeds into regenerating areas by comparing germination and seed removal rates between the regenerating areas and other vegetation types.


Lambert JE. Seed handling in chimpanzees (Pan troglodytes) and redtail monkeys (Cercopithecus ascanius): implications for understanding hominoid and cercopithecine fruit-processing strategies and seed dispersal. American Journal of Physical Anthropology 1999;109(3):365-386.

Supplemental Keywords:

fellowship, spatial patterns, temporal patterns, large-seeded species, chimpanzee, Pan troglodytes, Nyungwe Forest Reserve, Rwanda, seed dispersal model, seed dispersers, deposition patterns, microsites, feces deposition, germination, germination plots, vegetation, vegetation types.

Relevant Websites:

2004 STAR Graduate Fellowship Conference Poster (PDF, 1p., 230KB, about PDF)

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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