In autumn 2020, in spite of restrictions imposed by the authorities due to the COVID-19 disease, both Operation Baltic ringing stations worked through the whole season (Bukowo: 4 August – 6 November, Mierzeja Wiślana: 13 August – 3 November). All the necessary sanitary requirements were applied, including limited numbers of people in the staff at the stations. Altogether 14339 birds were ringed – 8045 at Bukowo and 6294 at Mierzeja. These results were significantly lower than in the previous year (less than a half of the result in autumn 2019). When compared with the long-term average (1961-2019), the result at Bukowo was slightly lower (96,2% of the average) and the result at Mierzeja was clearly lower (57,2% of the average). Such comparatively low numbers were mostly due to a rather poor performance of the last-year dominants: the Great Tit and the Long-tailed Tit. The migration of the Great Tits was quite weak in 2020; still, with 1518 ringed individuals it was the most numerous species ringed at Mierzeja. At Bukowo, the Robin was the dominant. As for the Long-tailed Tits, they were virtually non-existing (only 25 inds. ringed at both stations); however, such huge year-to-year variation in numbers is typical for this irruptive species. Comparatively low numbers were also recored for several reed-dwelling species, particularly the Reed Warbler. On the other hand, some species occurred in quite high numbers, including the Wren (199 inds. ringed at Bukowo – the highest score in Operation Baltic history) and the Bearded Reedling (327 inds. ringed at Mierzeja – the second highest score for OB). Seasonal migration dynamics were quite similar at both stations, with three clear peaks from the end of September till the end of October.
The total number of recorded species was 103. Most of them were common European Passerines, ringed at Operation Baltic every year, but we also ringed several species which are very rarely recorded at our stations. Among them was the Black-throated Loon Gavia arctca and the Wigeon Mareca penelope (both second for OB), as well as a rare wader species – the Great Snipe Gallinago media (fifth for OB). The true highlights of the season were two Red-flanked Bluetails Tarsiger cyanurus (one ringed at each station, fifth and sixth for OB) – for this Siberian-breeding species 2020 was the best year in Poland (6 records). Altogether 30 foreign recoveries were recorded (much less than in 2019), mostly from NE Europe (Lithuania, Russia, Estonia), but we also caught birds with rings from Czech Republic (Wren) and Spain (Song Thrush).
Our fieldwork was supported by 117 people, who took part in our studies. Among them were 10 foreigners, coming from UK, Ireland, France, the Netherlands, Denmark and Italy. We are very grateful to all the ringers and volunteers for their help and effort – thanks to them we were able to add another year to the 60-year unbroken monitoring data set, despite the difficult time of the pandemic.
Great Snipe, 19 August, Mierzeja Wiślana (photo P. Bauer)
Autumn migration dynamics at Operation Baltic stations