Résumé
Local recruitment rate is an important component of lifetime reproductive success (review by Clutton-Brock 1988), particularly in bird populations (van Balen et al. 1987; McCleery and Perrins 1988). This is not surprising, since the recruitment rate combines several very distinct components: survival during the first year of life, fidelity of the survivors to their natal area, breeding activity of one year old individuals, survival rate of one year old non breeders, etc… Since these components are influenced by different biotic and abiotic variables (with, as a result, different selection pressures), the resulting overall recruitment rate is likely to show important variations, unless strong negative trade-offs exist between its components.