The Common Moorhen is a dark waterbird with a red forehead and a yellow-tipped red bill, found across much of Europe, Africa, and Asia. Its endangered Mariana Moorhen lives on Guam and in the Northern Mariana Islands. On the U.S. mainland, a similar red-billed marsh bird is usually the Common Gallinule (Gallinula galeata).
The two look very similar in a photo. On the U.S. mainland, location usually points to Common Gallinule; calls and careful review help with rare exceptions.
Why they get mixed upBoth have a red forehead and bill and a white side stripe.