Deer have antlers, walruses have tusks – here’s why so few birds have weapons of their own

There's plenty of aggression in the bird world, but little armed violence. Velvet Shearer, USFWS/Flickr, CC BY

Mating season in the animal kingdom can be dramatic, and sometimes violent. As an example, take deer clashing their antlers during the rut – nostrils flaring, hooves hammering the ground, grass flying everywhere, and that eerie silence before the thunderous collision. The winning buck gets access to the harem, while the loser must find other females to fight for.

Many other animals also have formidable weapons. They range from rhinoceros beetles’ pointy horns to fiddler crabs’ proportionally gigantic claws and the long tusks of walruses and narwhals.