Some birds have really silly names. Yeah, yeah, I know that the "white-browed tit-warbler" wasn't named after what it sounds like it was, but that doesn't change the fact that it's funny to modern ears.
The fact is that most birds gained their common names long before they meant what they do now. Sometimes, that results in something cheeky and funny, and sometimes it so perfectly matches the bird now that it's inconceivable that the name is unrelated.