Waterfowl hybridize more than any other type of bird, and Mallards are some of the most prolific when it comes to this behavior. I saw this bird yesterday, and was confused (for a while) about whether it was a Mallard/American Black Duck hybrid or just an immature/nonbreeding male.
But then he stretched his wings out and I got a clear view of the speculum patch, which was bordered with white: a sure sign of a Mallard and not an American Black Duck, and thus this bird was not a hybrid after all.
