Curr. Biol. doi:10.1016/j.cub.2009.04.061 (2009)

Mockingbird songs are more elaborate in species that live in more variable climates.

Carlos Botero of Cornell University in Ithaca, New York, and his colleagues analysed almost 100 separate recordings spanning 29 species of mockingbird collected from across the New World. Places where precipitation and temperature were more variable and less predictable had birds that sang more consistently, had a broader repertoire and were better at copying the calls of other species.

The researchers suspect that the correlation relates to a sexual display of fitness, either spurred by increased competition for limited resources and females in variable climes, or tracking with neurological adaptations needed to survive in an unpredictable world.