Włodzimierz Meissner, Szymon Bzoma, Piotr Zięcik, Magdalena Wybraniec
Ornis Polonica 2014, 55: 96–104
https://doi.org/10.12657/ornis.2014.2.1
Abstract: The first Polish breeding records of the Sandwich Terns come from 1929 and 1932–1936. During this period up to three pairs of the species nested in the estuary of the Vistula Śmiała River near the city of Gdańsk. In 1972 an unsuccessful breeding attempt of three pairs was recorded at the lake of Gardno. In 1977–1986 there was a colony of Sandwich Terns at the mouth of the Vistula cross-cut. In 1982 the colony hosted about 300 pairs, but in the successive years the colony size declined. In 1989 and 1991 few Sandwich Terns nested again at the mouth of the Vistula cross-cut, but only in 2006 they started nesting on a breakwater in Gdynia port, where 140 nests were recorded. The following year nests of Sandwich Terns were observed at the mouth of the Vistula cross-cut, where they had nested previously. In 2006–2013 the colony size ranged from 100 to 570 nests, reaching the highest values in 2009 (in 2014 at least 630 nests were found). Apart from the Sandwich Terns several other species nested on the same sandbank, such as the Common Terns Sterna hirundo (up to 360 pairs), Little Terns Sternula albifrons (up to 200 par), Herring Gulls Larus argentatus (up to 5 pairs), Black-headed Gulls Chroicocephalus ridibundus (up to 10 pairs) and one pair of the Oystercatcher Haematopus ostralegus. The production of nestlings, in years when the colony was not destroyed by high water, ranged from 0.6 to 1.2–1.4 young per a breeding pair. Apart from natural factors, such as high waters or storms, the most important threat for nesting Sandwich Terns constitutes tourism. The penetration of sandbans by terrestial predators has never been observed, but nests at the coast were always destroyed by foxes Vulpes vulpes.
Keywords: Mewia Łacha, nestling production, Sandwich Tern, Sterna sandvicensis, tern colony, the Gulf of Gdańsk
