Factors affecting recapture and stopover of European Blackcaps (Sylvia atricapilla) during autumn migration along the South-Eastern migration route in SE Slovakia

Abstract

As part of migration, birds interrupt their flight to rest and replenish energy at stopovers. In this study, we investigated various factors (weather, date of ringing, tape-luring method) affecting the proportion of recaptured Eurasian Blackcaps during autumn migration (August, 14 to November, 5) and factors (weather, sex, age, date of ringing, tape-luring method) affecting their stopover duration. We analysed a 20-year dataset (2006–2025) from Drienovec Bird Ringing Station (SE Slovakia) situated on the SE European migration route of birds. Among 66,673 ringed Eurasian Blackcaps 9.39% were recaptured within the same season. The proportion of recaptured individuals was significantly lower with the use of night time tape-luring than with the use of day playback and with no playback, respectively. Recaptures were also fewer later in the season, and on days with mild wind and clear sky without low-level clouds. The minimum stopover duration of recaptured individuals lasted from 2 to 75 days. Median was 5 days. Females stayed significantly, about one day, longer than males. Stopover duration decreased with the later date of ringing. Furthermore, the interaction between age and tape-luring method was significant. The stopover was significantly longer in adults than in juveniles when using the night playback. Eurasian Blackcaps showed longer stopovers during days colder than average, with strong wind or precipitation. Also, with high air pressure and low cloudiness, indicating good weather, stopover duration increased. Our data support not only the influence of factors such as weather, date of ringing and sex on the stopover ecology of Eurasian Blackcaps, but also document the effects of tape-luring.