Résumé
To investigate how thin-billed prions, Pachyptila belcheri, regulagte their chick-provisioning behaviour, we compared data from two seasons with different food availability (1992 and 1997) and increased the costs of foraging by using load bands during 1997. The 1992 breeding season was poorer than 1997, but during both seasons parents used a two-part foraging strategy, mixing long trips, when they built up body reserves, with short trips, when they used previously stored reserves and foraged to feed the chick.