Stones in regurgitation - White Ibis?

On Mon, Feb 14, 2005 at 08:25:44AM +1000, Robyn Howard wrote:
> I have not seen this before and have not witnessed White Ibis doing any such
> thing.   Do they normally use stones to help break up food, and do birds
> that do use stones usually regurgitate them?
> 
> Would appreciate any knowledge or comments.

They're probably gastroliths (aka gizzard stones); birds, crocodiles
and dinosaurs are known to use them for grinding food.

Some stones are regurgitated when they become smooth and less
effective at grinding; they are replaced by swallowing new stones.
Small stones may be passed rather than regurgitated.

-- 
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   Paul Taylor                           Veni, vidi, tici -
                    I came, I saw, I ticked.

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