Tiny snails survive digestion by birds
By ELLA DAVIES - BBC NATURE
Added: Mon, 11 Jul 2011 22:38:27 UTC
Thanks to Ryan for the link
Excreted snails can survive
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.
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 pond snails can survive being eaten by fish 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," explained researcher Shinichiro Wada.
They also studied the genetic differences of T. boeningi populations found across the island and discovered considerable variation.
Rather than only mating with nearby snails, these results suggested that different populations made contact despite their geographical isolation.
"Biogeography of wingless terrestrial invertebrates, in particular snails, is often faced with mysterious long distance dispersal patterns that can only be explained by hand waving arguments involving birds' feet or guts or cyclones," said Mr Wada.
"This is the first study showing that birds can indeed transport a substantial [number of] micro land snails in their gut alive."
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