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INTRODUCTION
Food abundance has a major influence on the reproductive performance of seabirds, either directly through the rate of resource input or indirectly through body reserves stored by the adults (e.g., Anderson et al. 1982, Monaghan et al. 1989, 1992, Aebisher et al. 1990, Ainley and Boekelheide 1990). Body reserves, measured as adult body condition, can provide information on local food supplies and, accordingly, have been suggested as an indicator of marine resources (Cairns 1987, 1992, Monaghan et al. 1991, Montevecchi 1993). Recent declines of sandeel (Ammodytes marinus) stocks in Shetland, for example, have "experimentally" shown convincing relationships between food shortage, adult body condition, and reproductive effort (Monaghan et al. 1989, 1992). Drent and Daan (1980) emphasized the importance of body condition as a predictor of breeding success in birds and postulated that the amount of reserves at the onset of breeding (i.e., the "capital"), shaped by environmental conditions, will act on the rate of energy expenditure devoted to breeding.
Among seabirds, petrels exhibit a particularly high rate of adult survival and a very low reproductive rate (Lack 1968). In these long-lived organisms, life history theory predicts a trade-off between current and future reproductive potential (Williams 1966, Stearns 1976) such that, when resources are scarce, adults abandon a breeding episode if risks to their survival are too great (Goodman 1974, Drent and Daan 1980). Thus, in the most highly pelagic seabirds, which are generally the most long-lived (Lack 1968, Weimerskirch et al. 1987), this trade-off should operate through the monitoring of body weight. One predicts that, in pelagic species, reproductive parameters will be highly sensitive to change in body condition.
In this paper, we examine relationships between adult condition at the onset of breeding (early body condition) and annual reproductive performances of three petrel species showing various life history traits (fore aging ranges and adult survival). Blue Petrels (Halobaena caerulea) forage over pelagic waters (Stahl et n al. 1985, Chaurand and Weimerskirch 1994a), and Thin-billed Prions (Pachyptila belcheri) exploit neritic-pelagic areas (Stahl et al. 1985). On the other hand, Common Diving Petrels (Pelecanoides urinatrix) are coastal feeders, especially at Kerguelen Island (Weimerskirch et al. 1989), and are shorter lived than Thin-billed Prions and particularly Blue Petrels (Croxall 1982; O. Chastel, H. Weimerskirch, and P. Jouventin,...