Tiny snails survive digestion by birds

Snails are able to survive intact after being eaten by birds, according to scientists.

Japanese white-eyes on the island of Hahajima, Japan feast on tiny land snails.

Researchers found that 15% of the snails eaten survived digestion and were found alive in the birds’ droppings.

This evidence suggests that bird predation could be a key factor in how snail populations spread.

The Japanese white-eye or mejiro is widespread in Japan but considered an invasive species in Hawaii

It is well known that plant seeds are dispersed by birds that eat fruit.

But in findings published in the Journal of Biogeography, researchers from Tohoku University, Japan investigated whether invertebrates could also spread in this way.

Previous research has shown that ponds snails can survive being eaten by fishes but the same was not known for land snails.

Studies of the diets of birds on the island of Hahajima identified the Japanese white-eye’s preference for the tiny land snail Tornatellides boeningi.

In the lab scientists fed the birds with the snails to find out whether any survived the digestive process.

“We were surprised that a high rate, about 15 percent, of snails were still alive after passing through the gut of [the] birds,”

Introduced Japanese white-eyes pose major threat to Hawaii’s native and endangered birds | Science Codex


Native birds Himantopus knudseni or Aeo feed at Kealia Pond on Maui <br />Click for Larger Image
Native birds, Himantopus knudseni or Aeo, feed at Kealia Pond on Maui
Click for Larger Image
In the late 1920s, people intentionally introduced birds known as Japanese white-eyes into Hawaiian agricultural lands and gardens for purposes of bug control. Now, that decision has come back to bite us. A recent increase in the numbers of white-eyes that live in old-growth forests is leaving native bird species with too little to eat, according to a report published online on September 17th in Current Biology, a Cell Press publication. The findings show that introduced species can alter whole communities in significant ways and cause visible harm to the birds that manage to survive.

"Native Hawaiian songbirds cannot rear normal-size offspring in the presence of large numbers of introduced Japanese white-eyes," said Leonard Freed of the University of Hawaii at Manoa. "Their growth is stunted."