Biometrics, moult and migration of Grey Plovers, Pluvialis squatarola, at Mida Creek, Kenya

Abstract

Ringing data for 269 Grey Plovers, Pluvialis squatarola, caught between 1977 and 1988 were analysed. Adults started primary moult soon after arrival in August and September. Mean starting date of adult primary moult was estimated to be 13 September, primary moult duration as 130 days. First-year birds had not started primary moult by early May. Body mass of adults in primary moult was stable from September to February, averaging 205 g, but increased at the end of the moult in March and April. Pre-migratory body mass was estimated at 268 g and would allow a non-stop flight as far as the southeastern Mediterranean or the northern Persian Gulf. Mean wing length increased in March and April, possibly due to the arrival of longer-winged migrants from southern Africa or an earlier departure of males. A decrease in numbers was observed from the second half of April and by mid-May all adults had left the area. In June/July, the number of first-year birds was c. 25% of the total summer population.