Marie Read / Wood Ducks (Aix sponsa), females behave aggressively toward a male (second from right) that is trying to join them on a floating log, autumn, New York, USA, October.

Marie Read / American avocets (Recurvirostra americana) two during aggressive (territorial) encounter, Bear River Migratory Bird Refuge, Utah, USA, May.

Marie Read / Crested caracaras (Caracara cheriway), midair aggressive interaction between two for access to perch, Martin Refuge, Rio Grande Valley, Texas, USA, March.

David Pike / Two Collared peccaries (Pecari tajacu) drinking from pond, after aggressive altercation. January.

David Pike / Two Collared peccaries (Pecari tajacu) sniffing ground near pond, foraging for roots, grubs and prickly pear cactus, after aggressive altercation. January.