Micro-habitat selection of Bewick's Swans at rice fields in the Echigo Plain

Abstract

Micro-habitat selection within rice fields by Bewick's Swans Cygnus columbianus was investigated at Nishi- Kambara District in the Echigo Plain, Niigata, on December 11, 2004 and February 26, 2005. Swans preferred foraging sites in the basins of rice fields over sites along dikes and waterways. Statistical comparisons showed that the birds were observed to forage in basins at a greater frequency than would be expected if they were distributed at an equal rate in both micro-habitats. Conversely, birds which were not foraging were observed along dikes and waterways more often than predicted by chance. The area size of basins is much larger than the area for dikes and waterways, and this differential is addressed by the statistical method.