Feeding on caimans

Butterflies and bees were caught drinking caiman tears at La Selva biological reserve in Puerto Viejo, Sarapiquí.

In an inverse of our recent coverage of crocodilians in Costa Rica, we bring you the findings published by La Selva’s director, Carlos de la Rosa, on Thursday. De la Rosa reported the unexpected encounter involving a spectacled caiman (Caiman crocodilus) relaxing on the Puerto Viejo River last December.

“The fact that I was able to get that close with both a bee and a butterfly was very fortuitous,” de la Rosa said in a phone interview.

De la Rosa said the butterfly fed out of the caiman’s eye-socket for 15 minutes, while the relaxed reptile failed to even blink. The butterfly and bee were seeking the salt from their tears, a scarce resource in their environment, according to de la Rosa, adding that the tears could contain proteins and other micronutrients that help the insects survive.

The caiman’s placidness was striking to de la Rosa, but not all animals are as tolerant.

“However, I’ve seen these bees approach river turtles and the turtles are not as tolerant or pleased, shaking their heads and eventually even jumping back on the water,” De la Rosa said.

After returning to the station, de la Rosa looked up past research on what researchers called “lacryphagous” insects. After reading about bees feeding on human tears in Thailand, de la Rosa found a 2012 study where bees fed on turtle tears in the Ecuadorian Amazon.

“Although plentiful in the oceans, this element is in short supply on land, particularly in plants, which is why many terrestrial herbivores crave salt,” researchers Olivier Dangles and Jérôme Casas wrote. “Many species of insects, including several types of butterflies and moths, frequently visit moist ground and the excrement and carcasses of animals to obtain the dissolved nutrients they contain.”

De la Rosa, who normally works on flies, said the observation raised fascinating questions about the ecology and conservation of the area. If caimans and other river reptiles disappeared, would these insects be able to survive? And, if they could not, what effect would that have on the plant life in La Selva region?

“It shows that everything is connected,” De la Rosa said.