Cover picture: The rufous-collared sparrow (Zonotrichia capensis) breeds seasonally on the equator in Ecuador. Local populations breed asynchronously, associated with variations in local climate and independent of photoperiod. Males only sing during the breeding season and thus display associated asynchronous changes in structure of the neural song control system between two populations in close proximity. For details, see the article by Moore et al. in the November 10, 2004 issue (pages 10182–10185).