THE ABUNDANCE OF BREEDING KNOT CALIDRIS-CANUTUS ISLANDICA

Six sites around Borup Fiord, west central Ellesmere Island, Canada, w ere surveyed for breeding Knot Calidris canutus islandica. Breeding de nsity at the main study site was estimated using a calculation based o n hatching success, brood counts and the probability of broods being r esighted: estimates from other sites were based on this assessment. De nsity at the main study site was 4.6 pairs/km(2), varying between 0.4 and 12.7 pairs/km(2) in different areas. Density was negatively correl ated with spring snow cover. At other sites density estimates ranged f ront nil to 5.7 pairs/km(2). Brood counts and registrations of territo rial activity accounted for only 33% and 67% of pairs, respectively. A literature review suggested that within the Knot's breeding range, de nsities appear to be highest in areas showing a warm regional climate, early snow-melt, and high vegetational diversity and density. The Kno t's dependence on such areas may be related to its sire and need for a n early start to breeding. The total breeding population of C.c.island ica was estimated to be 61 000 pairs, or 304 000 individuals in autumn . Over-optimistic estimates of breeding numbers and productivity, howe ver, may mean that about half of the Knots wintering in Europe may not be C.c.islandica.