What is "kirr"

Kirr is an island in the Darss-Zingst Bodden Chain south of the Zingst Peninsula on the German Baltic Sea coast. It is separated from the peninsula by the Zingster Strom. The island is a nature reserve within the Western Pomerania Lagoon Area National Park. It was formerly and is sometimes still called Großer Kirr or Große Kirr ("Great Kirr"). This is to distinguish it from the northwestern part of the island, which was still a separate albeit much smaller island in the Zingster Strom in the second half of the 20th century, that used to be called Kleiner Kirr or Kleine Kirr ("Small Kirr").