Attributes / relations provided by
♦ ¹Winter feeding ecology and trophic relationships of Oldsquaws and White-winged Scoters on Kachemak Bay, Alaska, Gerald A. Sanger and Robert D. Jones, Jr., Canadian Wildlife Service, 1984
♦ ²R. W. Summers , S. Smith , M. Nicoll & N. K. Atkinson (1990) Tidal and sexual differences in the diet of Purple Sandpipers Calidris maritima in Scotland, Bird Study, 37:3, 187-194