SITE FIDELITY IN HIGH ARCTIC BREEDING WADERS

The return rate and fluctuations in density between years were determi ned for colour-marked populations of Grey Plover Pluvialis squatarola, Little Stint Calidris minuta, Curlew Sandpiper C. ferruginea, Sanderl ing C. alba and Knot C. canutus in a study in the Knipovich Bay area, northern Taimyr, Central Siberia (76 degrees 05'N, 98 degrees 32'E) du ring three breeding seasons, June 1990 to August 1992. No birds marked as chicks were recorded as returning to the study area. Females of al l species exhibited low site fidelity. The return rate of males varied between species. No marked male Curlew Sandpiper or Little Stint were recorded in the season following the marking, which is compatible wit h the nomadic behaviour of these two species. In contrast, males of Gr ey Plover and Knot were site faithful and had return rates of 78% and 63% respectively (though the latter value may have been underestimated ). Site fidelity of Sanderling males lay between these extremes (the r eturn rate was 20%). The variability of bird breeding density in the s tudy area was negatively correlated with return rate and reached the l argest value in Little Stint (a factor of 18,0 between the lowest and highest densities) and Curlew Sandpiper (factors of 4,4 for males and 5,7 for females), being intermediate in Sanderling (2,5) and the small est in males of Grey Plover (1,25) and Knot (1,4). In the late and col d season of 1992, bird densities were smallest in all species and the largest proportion of site faithful, but unmated, males of Grey Plover and Knot were recorded. Species with highly opportunistic and compara tively conservative territorial connections can be recognised among Si berian High Arctic waders. All species appear to show some degree of o pportunism, which is probably dictated by a number of factors of which climate is the most important.