This dirty looking Ibis is actually a not-quite adult. Juvenile White Ibis are brown and gradually turn white.

This one was foraging along the edge of a pond, sticking to the mostly shaded edge, quickly swallowing any food.

He stepped into the sun for a moment and you can see the mottled brown on his wings.

Wow! Wonderfully written. I love the white Ibis!
Thanks! The Ibis are a fun bird to watch as they poke along.