Frugivory and Seed Dispersal by Crocodilians: An Overlooked Form of Saurochory?

Authors

S. G. Platt, Wildlife Conservation Society
R. M. Elsey, Louisiana Department of Wildlife and Fisheries, Rockefeller Wildlife Refuge
H. Liu, Department of Earth and Environment, Florida International University; Center for Tropical Plant Conservation, Fairchild Tropical Botanic GardenFollow
T. R. Rainwater, United States Fish and Wildlife Service
J. C. Nifong, Department of Biology, University of FloridaFollow
Adam E. Rosenblatt, Department of Biological Sciences, Marine Sciences Program, Florida International UniversityFollow
Michael R. Heithaus, Department of Biological Sciences and Marine Sciences Program, Florida International UniversityFollow
F. J. Mazzotti, Department of Wildlife Ecology and Conservation, Fort Lauderdale Research and Education Center, University of FloridaFollow

Abstract

Saurochory (seed dispersal by reptiles) among crocodilians has largely been ignored, probably because these reptiles are generally assumed to be obligate carnivores incapable of digesting vegetable proteins and polysaccharides. Herein we review the literature on crocodilian diet, foraging ecology, digestive physiology and movement patterns, and provide additional empirical data from recent dietary studies of Alligator mississippiensis. We found evidence of frugivory in 13 of 18 (72.2%) species for which dietary information was available, indicating this behavior is widespread among the Crocodylia. Thirty-four families and 46 genera of plants were consumed by crocodilians. Fruit types consumed by crocodilians varied widely; over half (52.1%) were fleshy fruits. Some fruits are consumed as gastroliths or ingested incidental to prey capture; however, there is little doubt that on occasion, fruit is deliberately consumed, often in large quantities. Sensory cues involved in crocodilian frugivory are poorly understood, although airborne and waterborne cues as well as surface disturbances seem important. Crocodilians likely accrue nutritional benefits from frugivory and there are no a priori reasons to assume otherwise. Ingested seeds are regurgitated, retained in the stomach for indefinite and often lengthy periods, or passed through the digestive tract and excreted in feces. Chemical and mechanical scarification of seeds probably occurs in the stomach, but what effects these processes have on seed viability remain unknown. Because crocodilians have large territories and undertake lengthy movements, seeds are likely transported well beyond the parent plant before being voided. Little is known about the ultimate fate of seeds ingested by crocodilians; however, deposition sites could prove suitable for seed germination. Although there is no evidence for a crocodilian-specific dispersal syndrome similar to that described for other reptiles, our review strongly suggests that crocodilians function as effective agents of seed dispersal. Crocodilian saurochory offers a fertile ground for future research.

Comments

The definitive publisher-authenticated version is available online at http://dx.doi.org/10.1111/jzo.12052

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Platt, S.G., R.M. Elsey, H. Liu, T.R. Rainwater, J. Nifong, A.E. Rosenblatt, M.R. Heithaus, F.J. Mazzotti. 2013. Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory? Journal of Zoology DOI: 10.1111/jzo.12052