Sex-specific migration patterns and population trends of SkylarksAlauda arvensisringed during autumn migration in southern Italy
The autumn migration of Skylarks Alauda arvensis along the southern Tyrrhenian coast of Italy from 1998 until 2014 is described, with respect to timing and phenology, sex-specific migration patterns and population trends. In total, 21,610 fully grown birds were captured and ringed, using mist nets, from October to mid November. The frequency distribution of wing length shows a clear bimodality due to sexual dimorphism, with males having longer wings than females. Wing length was used to determine sex in 20,622 individuals using Harding–Cassie plots: 57.1% were identified as females, 38.3% as males and 4.6% were undetermined. Autumn migration of Skylarks peaked during the second and third 10-day periods of October. Females migrated earlier than males: the median date of migration, based on combined data for all years, was 19 October for females and 25 October for males. The main migration period, expressed as the interquartile range, fell between 12 and 26 October for females and between 17 and 29 October ...