Who's In Charge Here?

Like dogs, it seems the smaller the bird, the fiercer the bird. How many times have we seen, say, a mockingbird harassing a much larger crow or owl? The fiercest of all seems to be the hummingbird. Our alpha female this year looks to be more aggressive than usual. She has developed the habit of "inspecting" seed and suet feeders and every now and then buzzing a bird who in her view is out of line, or so it seems to my human eye. What strange behavior! The other birds do appear to give her a wide berth during these patrols. I haven't seen this hummer take on one of the ill-tempered catbirds, White Breasted Nuthatches, or Mockers yet, but I have no doubt they will get the raw end of that deal. Fun to watch...for me.