A few years ago Brito et al. (2002) published a brief but very interesting little paper in which they reported frugivory in Broad-snouted caimans Caiman latirostris. Two captive Brazilian animals were observed and photographed feeding on the fruit of Philodendron selloum [photo here is Fig. 1 from Brito et al. (2002)]. They later offered fruit to the caimans again “and frugivory was confirmed with other caimans from the pen” (p. 96: the ambiguous wording indicates that other individuals were happy to accept and eat the fruit as well). Apparently, herbivory has been recorded on quite a few occasions in crocodilians, but the general feeling is that such acts were accidental, with the animals presumably ingesting bits of plants when grabbing at animal prey. New observations imply, however, that herbivory might be far more widespread, and perhaps more important, in crocodilians than thought.
As reported on the St. Augustine Alligator Farm Zoological Park website, captive American alligators Alligator mississippiensis were observed eating from elderberry plants in 2000, and were definitely eating plant material (rather than grabbing at small animals lurking in the foliage). Alligators at the park have also been seen to eat lettuce leaves and squashes from bowls put out for tortoises, and this behaviour was commonplace enough for it to be filmed. Some of the alligators have been observed eating kumquats, oranges, lemons and limes. The video sequence included here shows an American alligator eating kumquats. Honest.
What gives? Do these observations indicate that extant crocodilians are not strict carnivores, and that fruits and even leaves are a normal supplement to their diet? We don’t know, field observations are needed. There is another, equally interesting possibility however: this being that the captive animals that we’ve been looking at have been mimicking other species. At least some of the alligators at the St. Augustine Alligator Farm Zoological Park are kept with tortoises, and have been eating the food put out for the tortoises. And as for the fruit-eating Brazilian caimans, Brito et al. (2002) drew attention to the fact that they were kept together with tegus Tupinambis merianae, and tegus are well known for eating fruit. Might the caimans therefore have seen the tegus eating fruit, and therefore “acquired frugivory behaviour from the tegus” (Brito et al. 2002, p. 96)); or, in other words, copied them.
It seems to me to be quite a sophisticated thing for an individual of species 1 to watch a member of species 2 perform an act that is alien to species 1 and to then mimic it, but evidence indicates that crocodilians really are quite sophisticated creatures, and probably smarter than is generally realised. Eating fruit when you have a skull and dentition suited for eating meat is – it seems – not difficult, and in fact carnivores may make the transition to some kinds of herbivory quite easily. Examples among mammals include red pandas, and procyonids like kinkajous. Among reptiles there’s the herbivorous raptor, Gypohierax angolensis, the Palm-nut vulture. We await more data on this very interesting subject.
Thanks to Tim Isles for heads-up on the St. Augustine website.
Refs – -
Brito, S. P., Andrade, D. V., & Abe, A. S. (2002). Do caimans eat fruit? Herpetological Natural History, 9, 95-96