EPOW - Ecology Picture of the Week

White-throated (=White Faced) Capuchin Monkey (Cebus capuchinus)
Manuel Antonio National Park, Costa Rica

Explanation:  Tropical forests of the New World (the Neotropics) are complex places with hundreds of tree species.  How do trees spread their seeds and remain viable in the face of so much potential competition for growing space?

One answer lies in animals that eat their fruit -- frugivores -- and disperse their seeds to germinate in locations away from the source tree.  In fact, tropical forests often exhibit closely evolved associations of frugivores and fruit-bearing trees. 

Primates constitute some of the major seed-dispersal agents in many tropical forests of the world.  Here is a white-throated capuchin monkey (also called white faced capuchin) of lowland Pacific tropical forests of Costa Rica in Central America. This monkey eats ripe fruits and arthropods, and is a key seed disperser for a wide variety of tree species. In one study of this monkey in Panama (Wehncke et al. 2003), it was found that they ate fruits from 95 of the 240 tree species available and dispersed seeds of most or all of those eaten.  

Further, the monkeys traveled far in their home ranges which averaged over 150 hectares (370 acres), moving 1-3 kilometers (0.6-1.8 miles) per day, and thereby when they defecated or spat out the seeds, they dispersed them far and wide.  Seeds were dispersed an average of 216 meters (709 feet) from the source tree, which is substantially farther than gravity alone could cast the seed.  These little monkeys spend much of the day traveling and feeding among a wide array of habitats including mature, disturbed, and secondary evergreen and deciduous forests (Emmons 1997).  

Information:
     Emmons, L. H. 1997. Neotropical rainforest mammals: a field guide. 2nd edition. University Of Chicago Press, Chicago, IL. 396 pp.
     Norconk, M. A., B. W. Grafton, and N. L. Conklin-Brittain. 1998. Seed dispersal by Neotropical seed predators. American journal of Primatology 45:103-126.
    Wehncke, E. V., S. P. Hubbell, R. B. Foster, and J. W. Dalling. 2003. Seed dispersal patterns produced by white-faced monkeys: implications for the dispersal limitation of neotropical tree species. Journal of Ecology 91(4):677-685.