The tears contain sodium, an important mineral that is scarce in the region and is essential for the survival of some herbivores like butterflies. Although turtles obtain sufficient sodium from their largely carnivorous diet, some other animals, including butterflies, find it challenging to get enough of the mineral. Butterflies also drink sodium from other sources like animal urine, muddy river banks, puddles, and even sweating people.
Geoff Gallice, a graduate student of entomology, has observed that the western Amazon rainforest is lower in sodium compared to many other parts of the world, as it is cut off from wind-borne mineral particles from the Atlantic Ocean by the Andes Mountains. Although minerals and dust make their way into the Amazon from the east, most of it is removed by rain before it reaches the western Amazon.
The impact of this teary endeavor on the turtles is not completely clear, but it probably has little impact other than making them more vulnerable to predators. The sight of butterflies flocking to the heads of the skittish reptiles to drink their tears is unique, and the phenomenon once again highlights the incredible adaptability of the creatures in their quest for survival.