Walking in a small park near my house on the Stanford campus one Fall morning, I heard the song of the California Thrasher; they regularly sing in September and October. I located the bird in a tree, then watched it fly downslope to a street below me. It was soon joined by a second thrasher, and then a third arrived. The original singer and the third bird then had the battle shown in these images. It may be that the second bird was a female, and the battle was over her, between two males. Or it could be that the fight was territorial, with either one of an established pair fighting against an intruder, following the script laid down in the BNA species account for California Thrasher: "Territory established and defended by both members of pair; territory borders often disputed with neighbors. Fighting occasionally observed, when disputants scrabble with each other vigorously on ground, wings beating, sometimes rising interlocked into air with legs and bills thrusting..."