The role of breeding success and parental care in determining sexual differences in the timing of southward migration of the Curlew Sandpiper Calidris ferruginea through Tunisia

The effects of breeding success on the timing of Curlew Sandpiper Calidris ferruginea southward migration through Tunisia were analysed using ringing data collected from 1971 to 1981. In years of low production and high predation pressure on the breeding grounds, female migration occurred on dates similar to male passage. In years with high breeding production, female migration occurred later in comparison with poor breeding years. No such relationships occurred in the timing of male migration. It is concluded that breeding success and patterns of parental care correlate with the timing of female migration, and annual fluctuations in breeding success with differences in the timing of passage of males and females.