17 August 2007
Vol 317, Issue 5840

About The Cover

Cover image expansion

COVER In superb fairy-wrens (Malurus cyaneus), helper males can assist females by providing extra food to their chicks. When this is the case, females lay smaller eggs that give rise to lighter chicks. Females benefit from increased survival. See page 941. Photo: BIOS Ruoso Cyril/Peter Arnold Inc.