The Costs Of Cooperation And Conflict In Group Living

“What do women want?” The same as what female ostrich want! The evolutionary pros and cons of group living are different for males and females, according to a newly published study of ostriches

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A group of wild ostriches (Struthio camelus) in the savannah. Masai Mara National Park, southwest Kenya. (Credit: Behn Lieu Song / CC BY-SA 2.0)

Raising children is a cooperative effort in humans — and in ostrich, Struthio camelus. Ostriches form groups that lay their eggs in a large communal nest and individual members of the group take turns incubating them. It seems very idyllic and cooperative until you realize that, like everything, cooperative breeding has its costs. For example, competition can be fierce over mating opportunities and whose eggs are incubated. The counteracting forces of cooperation and competition are predicted to select for an optimal group size, so knowing this, you might think that ostrich have precisely worked out the most beneficial group size and the best male-female balance within them. If so, and if real-life scenarios are anything to go by, you’d be wrong.

“The competing forces of competition and cooperation are expected to result in there being an optimal group size in nature”, said lead author, ecologist Julian Melgar, a postdoctoral researcher at Lund University. “But in the wild, groups are highly variable in size and it is not clear why.”