Spatial and temporal distribution of Southern Grey Shrikes Lanius meridionalis in agricultural areas

Capsule Southern Grey Shrikes were spatially segregated by sex during the non-breeding period. Aims To provide data that show sex-related spatial segregation in Southern Grey Shrikes in agricultural areas and suggest possible causes. Methods Shrikes were captured using a modified potter trap in a 169-km(2) study area in the Duero River valley, western Spain, which encompassed areas of irrigated and non-irrigated crop lands. Birds were sexed and colour-ringed, and capture locations and re-sighting locations plotted with respect to irrigated and non-irrigated crop systems Results A total of 215 shrikes were trapped. Males occupied the breeding areas (non-irrigated crops) year-round, and only 12.8% moved to irrigated crops during the non-breeding months. Females occupied irrigated crops in the autumn (94.9% in October and November), and in January they started to return to the breeding areas. The movements of females were greater in length than those of males between different periods (breeding, non-breeding), but not within the same period. Conclusion In the study area the Southern Grey Shrikes were spatially segregated by sex and we suggest that this arises because females are subordinate to males.