Rekordowa koncentracja noclegowa śmieszki Chroicocephalus ridibundus w Warszawie

• Autorzy: Sidelnik M. , Rapczynski J.

Warianty tytułu

EN

Record concentration of Black-headed Gull Chroicocephalus ridibundus roosting in Warsaw

• Języki publikacji: PL

Abstrakty

EN

Black-headed Gull Chroicocephalus ridibundus is the most numerous gull species in Poland, although its non-breeding abundance seems to be poorly described. In 1985–1990 whole wintering population was estimated at 19 000 individuals in the time of harsh winters to 48 000 in mild winter. The greatest concentration during autumn migration that can be found in the literature was 24 300 inds at Nyski Reservoir and the highest number during spring migration, provided via ornitho.pl portal until end of 2020 was 20 000 at Mietkowski Reservoir. On 4 March 2021, the authors of this paper carried out the count of gulls gathering at roost site of Osadnik Czerniakowski in Warsaw. To count all the birds present in the area, aerial photographs were taken by the drone, later on they were processed by Fiji program for automatic counting of every individual. To determine Black-headed Gull to Common Gull Larus canus ratio, photos from 500 mm lens were taken as a sampling method, giving the score of 87,7% for Black-headed and 12,3% for Common Gull. This ratio has been extrapolated for the whole flock of 48 384 inds. As a result, the number of Black-headed Gull was established at 42 441 inds.

• Wydawca: -
• Czasopismo: Ornis Polonica
• Rocznik: 2022
• Tom: 63
• Numer: 1
• Opis fizyczny: s.67-71,fot.,bibliogr.

Twórcy

autor

Sidelnik M.

• [e-mail]

autor

Rapczynski J.

• Koło Naukowe Leśników, Sekcja Ornitologiczna, SGGW, Nowoursynowska 166, 02-787 Warszawa