Red in tooth and claw

… and beak. Acorn Woodpeckers (Melanerpes formicivorus), it turns out, can be fierce fighters when defending a granary tree.

Each combat site lured up to 50 helper females representing a dozen or more competing coalitions. The birds spread their wings to put on a show of superiority and strength and engaged in incessant bickering; at times the war got bloody. “We’ve seen birds with eyes gouged out, wings broken, bloody feathers, and birds that fell to the ground fighting each other,” Dr. [Sahas] Barve said. “It’s the real stuff.”