SEASONAL-CHANGES IN SONG NUCLEI AND SONG BEHAVIOR IN GAMBELS WHITE-CROWNED SPARROWS

In males of several songbird species, the morphology of forebrain nucl ei that control song changes seasonally, The only seasonally breeding songbird in which seasonal changes in the structure of song control nu clei have been reported not to occur is the nonmigratory Nuttall's sub species of white-crowned sparrow, In the present study, we manipulated photoperiod and plasma testosterone concentrations in captive male wh ite-crowned sparrows of the migratory Gambel's subspecies, Males expos ed to photoperiods and plasma testosterone concentrations typical of t hose experienced by wild breeding males had larger song control nuclei than males held on a winter photoperiod, We also found seasonal chang es in stereotypy of spectral and temporal parameters of song in wild G ambel's white-crowned sparrows, We hypothesize that seasonal changes i n the song control nuclei may correlate with seasonal changes in song stereotypy. (C) 1995 John Wiley & Sons, Inc.