Résumé
Demographic parameters of the polygynous Rock Sparrow Petronia petronia were investigated in a small patchy population in the Italian Alps. The population included two distinct breeding patches that differed in altitude and breeding success. Survival parameters were estimated by capture-recapture analysis of 170 individually marked animals. At the whole population level (Cormack-Jolly Seber model), no sex difference in local survival probability was detected. We then used a multisite capture-recapture approach (Arnason-Schwarz model) to investigate patch-specific survival probability and between-patch dispersal rate conditional on survival. Female local survival in the higher-altitude patch (mean ± se: 0.54 ± 0.04) was significantly greater than in the other patch (0.37 ± 0.04), probably because permanent emigration from the study area was greater. In the higher-altitude patch, breeding dispersal was constrained by the altitude limit and breeding movements were directed toward the patch at lower altitude. The probability of changing patch in the next breeding season was significantly higher for females (range 0.16-0.21) than for males (0.01-0.03). Breeding success varied between years and patches, being lower in the patch where frequency of polygamy and female local mortality were higher. Dispersal probability is increasingly being taken into account in theoretical and empirical studies