Both belted kingfishers I saw yesterday appeared to be adult females. And by their behavior, calling to each other before joining up for some aerobatic frolics, I would say they were definitely related! I love the inversion one of the birds is pulling in the first photo. In the second photo, there's a big splash from a frightened duck diving in alarm as one of the ladies buzzes too near it. No idea if she meant to do that!