Researchers find carnivorous crocs enjoy a taste of fruit

FIU researchers have found that the American alligator, and a dozen species in the crocodilia order, enjoy a taste of fruit along with their usual meat-heavy diets of birds, fish and mammals.

This comes as news to biologists because it has long-been assumed that crocodilians are true carnivores incapable of digesting fruit and vegetable proteins and polysaccharides, a type of complex carbohydrate.

Heithaus (left) and Rosenblatt (right) get ready to pump the stomach of an American alligator in the Everglades in 2011. Photo by Josh Goodstein.

The study, led by the Wildlife Conservation Society, includes Mike Heithaus and Adam E. Rosenblatt ’13 from FIU’s Department of Biological Sciences and Hong Liu of the FIU Department of Earth and Environment, as well as researchers from the U.S. Fish and Wildlife Services, Louisiana Department of Wildlife and Fisheries, and University of Florida.

“Crocodilians are some of the largest predators in many freshwater and estuarine environments around the world.” said Heithaus, executive director of the School of Environment, Arts and Society, professor of marine sciences and predator expert. “Finding they eat fruit is a bit surprising since they’re equipped with such big mouths and teeth for taking out big prey. It leads to the question of whether they play more roles in ecosystems than we previously thought.”

The researchers examined 18 species of crocodilians, including the American alligator, Nile crocodile, Indian crocodile, caiman crocodile, saltwater crocodile, American crocodile and dwarf crocodile. They found 13 of these consumed some form of fruit, including berries, legumes, nuts, grains and other fleshy fruits. While the researchers say some of the fruit ingestion may have been due to prey capture, evidence shows that other fruit is consumed deliberately and in large quantities.

In addition to providing new insight on the diets of crocodilians, the study also gives insight into the role they might play in forest regeneration through digesting and passing fruit seeds.

“Alligators and crocodiles are highly mobile animals that can move long distances. If they excrete seeds in different areas, they could possibly be actively spreading those seeds and changing the distribution of plants in the environments where they live. We see the same pattern with birds. That type of activity can have a big impact in the ecosystem,” said Rosenblatt, a post-doctorate researcher at Yale University and former Ph.D. student of Heithaus.

Further research is needed to learn how crocodilians process carbohydrates and other plant-based nutrients, as well as of the nutritional rewards crocodilians gain by eating fruit.

The study, formally titled “Frugivory and seed dispersal by crocodilians: an overlooked form of saurochory?,” was published in the July issue of the Journal of Zoology.