Document Type


Date of Degree Completion

Spring 2017

Degree Name

Master of Science (MS)


Primate Behavior

Committee Chair

Jessica A. Mayhew

Second Committee Member

Lori K. Sheeran

Third Committee Member

Daniel D. Beck


In this study, I investigated the potential effect of howler monkey (Alouatta palliata) defecations on the diversity and abundance of seedlings on the forest floor of a tropical lowland forest in Bocas del Toro, Panama. I conducted follows on a howler monkey group for 18 days and found six trees the monkeys used for sleeping. During this time, I collected feces and extracted the ingested seeds. I counted the seeds and identified the seed genus when possible. After this initial observation period, I constructed transects in random directions covering the entire tree crown underneath sleeping trees. I collected and counted every dicot seedling shorter than 30 cm. I identified the seedlings in the lab, to the species level when possible, and repeated the process in control transects of the same size in the same forest type, with comparable canopy cover and soil conditions. In total I identified 46 morphotypes from 967 individual seedlings, 676 underneath sleeping trees and 291 in control areas. Of the 46 morphotypes, I identified 16 to the species level, ten to the genus level, four to the family level, and 16 remain unidentified. Of these species, 12 were found exclusively in the sleeping transects, and 11 were exclusive to the control transects. I predicted that there would be greater individual seedlings and greater species richness, and diversity underneath the sleeping trees than in control areas. I also predicted that some plant species would be more prevalent underneath sleeping trees due to howler monkey dietary preferences and what was fruiting during this period. I did not observe a significant difference in seedling abundance, species richness, Shannon-Wiener diversity, or Gini-Simpson diversity (p values > .05). Taking into account the life history of some clumped seedling species, I attempted to determine whether they arrived there via howler monkey endozoochory. I also examined the effects of secondary dispersers such as dung beetles and rodents, and offer suggestions for strengthening this research for future study. This study contributes to our knowledge of how howler monkeys contribute to forest flora communities, and offers an important foundation for the forest floor community for other students interested in primate seed dispersal.