Song swans in Lake Frøland (Hallgeir B. Skjelstad)
Lake Frøland is perhaps the place in Hordaland where the song swan has over-wintered longest. They come here every year, and at the most nearly 30 individuals have been seen at one time. This locality is especially important in cold periods, when the water in for example Hålandsdalen in Fusa freezes over. Discharge of "warm water" from the Frøland power station makes the water in lake Frøland warm enough that it seldom or never freezes totally.
- Byrkjeland, S.; Voie, R. 1999. Sangsvanebestanden i Hordaland – 160% økning siden 1988. Krompen 28:176–187.