On June 6, 1919, the famous Swedish ornithologist Erik Rosenberg, at that time sixteen years old, arrived with the train at Hidingsta together with his biology teacher Sven G:son Blomqvist. They made an excursion through the reeds and marshes of Kvismaren and also visited Sörön and the Resta bog. This trip was the start of modern bird watching in the Kvismaren area. Before, Kvismaren was totally unknown from an ornithologists point of view.
Before lowering the water level of the large lake Hjälmaren the areas today covered with reed in East and West Kvismaren was open water. From 1877 to 1887 Hjälmaren and Kvismaren were lowered to gain more land for agriculture. Kvismaren was lowered some 1.5 m and most of the lakes were dried out. Kvismare canal was built to facilitate the lowering, and within a couple of years the former lake bottoms were covered with reed.
A restoration of part of the overgrown lake bottoms started in the beginning of the seventies, starting with the eastern part of Fågelsjön. In 1981-1982 lake Rysjön was restored and some years later also the western part of Fågelsjön. The restored lakes are checked and maintained continuously, e. g. by regulating the water level. In 1997 a second restoration was done in Rysjön.
Grazing of wetlands and shore meadows is another important part of the conservation work at Kvismaren. Hammarmaden as well as Nyängen and Fiskingemaden are grazed and normally good stop-over-places for migrating waders, ducks and geese.