Two year observations of a family of the Whooper Swan Cygnus cygnus at Hyoko, Niigata

Abstract

1. A particular female Whooper Swan and her family, wintering at a well known swan and waterfowl resort, lake Hyoko near Niigata City on Japan Sea coast of Honshu, were kept under observation of behavior in two successive winters. Here the swans (and other waterfowls) are well tamed by artificial feeding.
2. This particular female could be identified by a pair of small yellow spots on both sides of the black part of the bill.
3. In 1974-75 winter, she formed a family with her mate and four cygnets, but she returned in December 1975 with a male not accompanied by cygnets.
4. Continuous observations of 4.6 hours and 6 hours were made on February 14, 1975 and January 30, 1976 respectively.
5. Their movements were recorded every 2 minutes and the moving distance/per hour was 680m, on February 14, 1975 (with cygnets), and only 67m, on January 30, 1976 (withont cygnets).
6. Although the lake condition partly caused the above difference of moving distance/per hour in 1975 and 76, because most of the lake surface except artificial feeding place was frozen in 1976, but all the surface was free from ice in 1975, the difference of family composition in the two years, with or without cygnets, was apparently correlated as mentioned below.
7. The 1976 pair, without cygnets, responded quickly to the artificial feeding and after eating enough could rest on nearly ice not moving to a distance, but the 1975 family, with cygnets, arrived feeding place later than others and could not eat enough, thus moving away to continue feeding on natural food at other parts of the lake.