A young male Rufous Hummingbird (Selasphorus rufus) has established a territory at my feeders. He announces that he's "taken over" by continually chattering this one-note warning. When another hummer of any species enters his airspace, he "bounces" them by rushing at them and emitting the high-pitched warning beeps you hear near the end of this sample! Attentive listeners will hear a Flicker in the distance on the first sample.