Reciprocal altruism in birds

Unrelated passerine birds often join together while mobbing, a widespread antipredator behaviour during which birds harass a predator. Prey individuals may also warn each other about the approaching predators. Although previous analyses concluded that mobbing and alarm calls could not have evolved via reciprocity, this book shows that birds preferentially join mobs with neighbours that have aided them previously, suggesting that the birds may utilize reciprocity-based strategies involving individual recognition and recollection of previous interactions with others. This implies a level of sophistication in bird communities greater than had previously been realized adding a piece of new knowledge to reveal co-operation between unrelated individuals which is one of the most important question in evolutionary biology.