No idea! Interesting image though. Almost looks like part of something too large and sharp it ate protruded out - kinda like another bird's foot/claw. Difficult to tell.
Last edited by Daniel Cadieux; 06-02-2016 at 08:23 PM.
I have seen something like this on the egrets, too. Here is one example. I don't know if it's the same protrusion but it looks very similar from the look of it.