Karsiborska Kępa ( German Kaseburger Hutung ) is an uninhabited island in the rear delta of the Świna in the Szczecin Lagoon.
With an area of 280 hectares, the island is one of the larger of around 40 islands in the rear delta of the Świna. It is surrounded in the east, north and west by the Stara Świna (Old Świna) and its side arms Groblanka (Monks' Weir) and Młyńska Toń (Mill Hole). In the south it separates the Rzecki Nurt (Rickstrom) from the island of Karsibór (Kaseburg). The island is 3.2 km long and up to 1.7 km wide.
Like the entire delta, the island was formed by deposits of silt and sand carried along by the seawater that flows into the Szczecin Lagoon through the Świna River, mainly in autumn and winter. In the 1920s and 1930s, the Kaseburger Hutung was converted into a polder by dykes. The creation of drainage ditches made the island usable for grazing. In the 1970s there were up to 450 grazing animals (cattle, horses and sheep). After that, usage declined. The drainage ditches increasingly silted up and the area covered with reeds increased from 25% in the early 1970s to more than 50% today.
In 1995, the non-governmental organization Polish Society for the Protection of Birds (Ogólnopolskie Towarzystwo Ochrony Ptaków, OTOP) established a bird sanctuary on the island after purchasing around 180 ha of land. Reed areas in the north and south-east of Karsiborska Kępa and some pastures and meadows continue to be used privately. The island is part of the Important Bird Area "Swinedelta" designated by BirdLife International
Source: Wikipedia