Red Knot Calidris canutus migration at Grays Harbor and Willapa Bay, Washington: spring 2009

Red Knots Calidris canutus believed to be of the subspecies roselaari, migrate along the Pacific coast of North America and use localized areas of Grays Harbor and Willapa Bay, Washington, as stopover sites. As part of an effort to estimate the population size of Red Knots that use Grays Harbor and Willapa Bay during spring, we used airboats as observation platforms to facilitate making counts of knots and to search for leg flags during the 2009 spring migration. We made several site counts of >1,000 Red Knots and recorded a peak of about 4,000 birds at the Grays Harbor study area on 4 May. The peak of migration at Willapa Bay occurred on 30April. Most of  the higher counts of knots were made after the peak than before. We saw 146 leg flags and made positive flag code identifications of 91 individuals on 132 occasions. All flagged birds were marked in Guerrero Negro, Mexico, except for two birds marked on Wrangel Island, Russia. Aggregations of Red Knots were observed near the mouths of Grass Creek (Grays Harbor) and North River/Willapa River (Willapa Bay). These locations may be important, and possibly essential, foraging areas for knots during spring migration.