Østensjøvannet is a nutrientrich lake on the eastern side of Oslo, particularly rich of birds. It is surrounded by residential areas and lawns, some agricultural fields and a small coniferous forest, and is flanked by reed beds and deciduous woods and bushes. Encircling the lake is a walkway that is a popular hiking trail for the residents. Birds in Østensjøvannet are fed by people on a regular basis, making the birds very confiding. The dominant species in Østensjøvannet are Barnacle, Canada and Greylag Geese, Mallard, Tufted Duck, Goldeneye, Great Crested Grebe, Moorhen, Coot, Black-headed, Herring and Lesser Black-backed Gulls.