Sex-ratio and body size of sandpiper chicks at Zackenberg, north-east Greenland in 2003

There is growing evidence that female birds may adaptively bias the sex ratio of their young as a function of environmental conditions. Data on brood sex ratio in shorebirds are scarce, however. In this study we report the brood sex ratios and morphometrics of Arctic sandpipers. Sex was determined in 13–64 chicks of Sanderling Calidris alba, Red Knot Calidris canutus islandica, Dunlin Calidris alpina arctica, and Ruddy Turnstone Arenaria interpres in NE Greenland during the 2003 breeding season. Brood sex ratios were biased significantly towards males in Dunlin and Ruddy Turnstone, but in Dunlin this bias disappeared in chicks older than two days. There was a non-significant bias towards females in Sanderling and Red Knot. Only for bill length in Dunlin hatchlings, there were significant differences between males and females. Surprisingly, in contrast to their parents, male chicks had longer bills than female chicks.