Aims: The main aim of this study is to describe several poorly known aspects of the breeding biology of the Red-necked Nightjar Caprimulgus ruficollis.
Location: Córdoba, Southern Spain (37°55´N, 4°55´E).
Methods: We studied breeding success, laying phenology and nest movement in a population of 26 breeding pairs of Red-necked Nightjar during 1994 and 1995. During 1996, 1997 and 1998 we collected additional data on nest site reuse on 25 nests. For each nest, we considered the following measures of reproductive success: hatching success (proportion of eggs that hatched), fledging success (proportion of hatchlings that resulted in fledged young) and breeding success (proportion of eggs that resulted in fledged young). Statistical analysis was performed using Chi-Square test, Kruskal-Wallis test and Spearman correlation.
Results and Conclusions: Breeding success did not differ between years but we found significant differences within the season. In both years, successful nests were those with earlier laying dates than in unsuccessful ones. Laying phenology patterns were very similar for 1994 and 1995 with median laying date corresponding to 19 May. Clutch size did not differ between years but there were significant differences between successful and unsuccessful nests. We failed to find any evidence of nest movement during the incubation period but during the fledgling period nest movement was very common and our results do not support previous claims on nest movement during the incubation period. Several nests sites from 1994 were reoccupied during the following years, one of them for at least five consecutive years. Reoccupied nest sites were very successful and all the eggs laid in these nests produced fledglings.
