During a drought in 1976-78 on the island of Daphne Major in the Galapagos Archipelago, the population sizeof finches (Geospiza fortis) decreased (Graph A) due to the decline in seed supply (Graph B), during which time the size and hardness of the seeds increased (Graph C), as a result of which the average size of finches increased (Graph D), because larger birds can handle such seeds more efficiently.