GEOGRAPHIC-VARIATION IN THE CALL OF THE BLUE PETREL - EFFECTS OF SEX AND GEOGRAPHICAL SCALE

We examined geographic variation between sexes in calls of Blue Petrel Halobaena caerulea, and at macro- (five archipelagoes) and microscale s (seven islands). Using calls from 504 different individuals, we dete cted a significant geographic variation in males at both geographical scales, but not in females. Overall, the first syllables and silences, and some frequency parameters were highly variable between localities . In males, micro-and macroscale variations appeared equally significa nt, although more parameters were involved at a micro level. We discus s these results according to several hypothesis: vocal learning, envir onmental effect and population marker, and finally suggest that geneti c drift, coupled with strong philopatry, may account for these differe nces.