Abstract
Observations of Okinawa Rail Gallirallus okinawae feeding behavior and of cracked snail shells revealed a correlation between shell-cracking techniques using anvil stones and cracked shell types. Three infrared cameras were used to study rail behavior around stone anvils in the forests surrounding Kunigami Village, northern Okinawa Island. Snail shells were collected for analysis. Four individual rails were recorded smashing shells against fixed stone anvils; the first time this behavior has been described for the Okinawa Rail. Snail shells were classified into four types according to the manner in which they were cracked. It is suggested that rails cracked the majority of the shells (of two types) in order to feed on the snails. The use of anvils by rails to crack snail shells allows them to feed on snails that are too large to be swallowed whole, but which are commonly available on Okinawa Island.
