Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Acta Ornithologica 9-22 mate choice mate fidelity nest fidelity nest-site choice Procellariiformes reproductive performance sexual size dimorphism MEDITERRANEE FRANCE 2014 fdi:010062509 ENG Acta Ornithologica 0001-6454 ISI:000340994700002 1 10.3161/000164514x682850 https://www.documentation.ird.fr/hor/fdi:010062509 https://www.documentation.ird.fr/intranet/publi/2014/09/010062509.pdf 49 Horizon (IRD) Nest and mate choice is important in seabirds, influencing reproductive performance as both nest:site and partner quality varies. The Yelkouan Shearwater Puffinus yelkouan nests mainly in pre-existing cavities and to a lesser extent in cavities it excavates. We have monitored breeding colonies of the Yelkouan Shearwater on two islands of the Hyeres archipelago, south-east of France, for nine years to analyse nest-cavity and mate selection, to evaluate nest-cavity and mate fidelity, and to investigate their relationships with reproductive performance. Yelkouan Shearwaters selected nest-cavities providing a high degree of concealment and protection. Reproductive performance and fidelity to cavity were highest in deep cavities with a winding tunnel and a steep slope around the entrance. Mating was assortative for bill and tarsus measurements. High rates of return to the same cavity (94.7%) and mate (95.5%) were recorded. Fidelity to nest-cavity was highest when breeding succeeded the previous year (fidelity rate: 97.3% in successful breeders vs. 87.8% in unsuccessful breeders) and was most likely to result in successful breeding the same year (breeding success: 67.5% in faithful breeders vs. 43.8% in movers). The rate of divorce was low (4.5%), did not differ between islands and was not associated with breeding performance. However, breeding success increased by 22.2 +/- 9.9% after mate change following a divorce or the absence of a previous mate. Such high rates of nest-cavity and mate fidelity could indicate a good population status with breeding habitat, food resource and mates of good quality. 080 UR237