This study seeks to understand how variations in climatic conditions alter the reproductive cycles in three populations of white-crowned sparrows living in diverse habitats within a relatively small area of western Washington state. The research will integrate field and laboratory studies on reproductive function. Comparisons between populations will be made of behavior and reproductive state in the springtime and experimental manipulations of environmental cues suspected of signaling environmental change will be performed. The long range goal of the project is to determine the extent and function of pathways in the brain of these animals for environmental signals that regulate changes in appearance and behavior. Such information is critical to understand, in general, how animals react to their habitat to aid us in the future in solving problems associated with global warming and habitat destruction. Understanding the mechanisms by which vertebrates transform environmental information into morphological, physiological and behavioral adjustments may help us evaluate the extent to which species are able to adapt and how we may fare in a changing environment.