An agouti eating a palm seed in Panama. Photo by C. Ziegler.
An ocelot eating an agouti in Panama. Photo by C. Ziegler.
A palm seeding establishing after its seed escaped agouti consumption. Photo by P. Jansen
Patrick Jansen examining a seed we radio-tracked as it was dispersed, cached by an agouti, and later found and eaten.
Seed dispersal and seed predation by animals are key natural processes that affect forest regeneration and the evolution of plant diversity. The role of rodents in this regard is controversial, having been argued as good for trees because they disperse and burry seeds, bad for trees because rodents eat seeds, or conditionally mutualistic depending on local food or predators. This relationship remains uncertain because few studies have been able to follow seeds to determine their ultimate fate. This study uses motion-sensitive radio transmitters to track the fate of rodent-dispersed seeds. The hypothesis tested is that rodents are conditional mutualists of trees: they are effective dispersers only where seeds are at low density AND rodents have a high likelihood of dying, thus leaving their buried seeds to germinate.
The factors affecting whether rodents are dispersers or predators of seeds are of major importance for forest management, where rodents still tend to be viewed as pests that should be killed. Our study will provide a framework for understanding the role of rodents, and of how disturbances such as fragmentation and hunting affect forest regeneration by modifying predator and rodent abundances. Emphasis on scientifically interesting research with charismatic rainforest animals and important conservation implications will put the study in a strong position for continued involvement in educational programs.
Additional information and pictures about this project are available in the National Geographic Magazine article on our research.
Collaborations: Dr. Martin Wikelski, Princeton University and Dr. Patrick Jansen, University of Groningen.
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