No messing

The sharp, horn-covered bony projection on the wrist joint of some waterfowl is known as the Carpal spur. It is there for fighting! The Magellanic Steamerduck (Tachyeres pternes) and the Falkland Steamerduck (Tachyeres brachypterus) overlap in terms of range, but utilise a slightly different habitat. Probably just as well really, both are capable of fighting to the death when it comes to territory.
Falkland Steamerduck
Falkland Steamerduck showing carpal spurs — Frank Todd
Magellanic Sreamerduck
Magellanic Sreamerduck — Jonathan Beilby