Regional, seasonal and annual variations in the structure of Purple Sandpiper Calidris maritime populations in Britain

Samples of Purple Sandpipers were captured around the coasts of Britain. Analysis of their bill-length distributions enabled the sex ratios and percentages of 'long-billed' and 'short-billed' birds at each locality to be estimated. The sex ratio for the 'long-billed' population was estimated to be one female to 2–11 males, and one female to 1 -34 males for the 'short-billed' population. During winter, proportionately more 'long-billed' birds occurred in northern and western Scotland, Wales and southern England, whilst 'short-billed' birds predominated from Kincardine to Yorkshire. The total sizes of the 'long-' and 'short-billed7' populations were c. 15 000 and 4000, respectively. 'Short-billed' birds started arriving from Norway in early July. 'Long-billed' birds did not arrive until late October. Their origins are as yet unknown. No annual variations in the population structure were detected.