Scientists have recently discovered that certain species of snails are able to survive being eaten by birds. Results of experiments published in the Journal of Biogeography show that bird predation of snails may be used to help snail populations—specifically those on a small island in Japan—thrive.
The dynamic between a predator and its food is generally thought of as a way to keep populations of prey in check, limiting their dispersal. However, predation has also been known as a way to increase a prey’s dispersal, such as when plant seeds are dispersed by birds that eat fruit. The plant seeds are able to successfully pass through their digestive system, and are released in bird droppings, which provides key nutrients for them to grow. This is just one example of how predation can be used not only to limit the survival rate of a species, but to help one thrive as well.
Researchers from Tohoku University, Japan studied the diets of birds living on the island of Hahajima, Japan—specifically the Japanese white-eyes that live there—to investigate if invertebrates such as the land snails they feast on can be dispersed in ways similar to plant seeds.
The research team found that 15% of land snails eaten by Japanese white-eyes were able to survive their digestive systems intact, suggesting that bird predation may be a vital process by which snail populations are spread.
Birds Help Spread the Love
This is a huge find for scientists studying the variations of snails across Japan, as scientists have previously been unable to explain how past genetic testing has shown individual species of snails, mostly isolated to single islands across Japan, have been able to mate with species isolated to other islands. Now, scientists hypothesize that this is likely the case due to being flown across Japan in the guts of birds, from which they are later secreted, and free to mate with a wide variety of other land snails.
Previous studies have shown that pond snails can be swallowed up and dispersed by fish, but there was yet to be any studies done on land snails.