Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Michel Roggo / Dead Sockeye / Red Salmon (Oncorhynchus nerka) after spawning migration. Adams River, British Columbia, Canada, October.

Michael Hutchinson / Male Moorhens (Gallinula chloropus) fighting with clawing feet locked together, Gloucestershire, UK

Steven Kazlowski / Group of Wild Grey wolves {Canis lupus} with pair locked together after mating, Denali National Park, Alaska, USA

Michio Hoshino / Alaska Moose (Alces alces gigas) two skulls with antlers locked together in stream bed, males probably became fatally entangled while fighting, Alaska

Jim Brandenburg / Canada Jay (Perisoreus canadensis) perching on the antlers of two Moose (Alces alces andersoni) who locked antlers in battle and died together, Michigan