Hummingbirds are good at communicating. If you’ve ever seen a Hummingbird hovering in front of your window staring in, it’s usually an indication that their feeder needs attention. They know who fills the feeder. In this image, the White-necked Jacobin is relating his concern to another Jacobin, a female or juvenile, approaching his perch by glaring at the interloper and by flaring his tail. The glare and the flare are both threatening gestures. The Jacobin seems to be trying to claim that space as his. He didn’t succeed. The bird flew by and landed on a perch right next to him. I guess communication in the bird world can be as difficult as it is in our world.