A comparison between high water and low water counts of shorebirds on the Wash, east England

Abstract

Comparisons are made between counts of shorebirds at high water roosts and low water feeding grounds on the Wash, east England. During autumn and winter 1985–87, Shelduck, Tadorna tadorna, Oystercatcher, Haematopus ostralegus, Ringed Plover, Charadrius hiaticula, Grey Plover, Pluvialis squatarola, Knot, Calidris canutus, Dunlin, Calidris alpina, Bar-tailed Godwit, Limosa lapponica, Curlew, Numenius arquata Redshank, Tringa totanus and Turnstone, Arenaria interpres were counted at roost as part of the Birds of Estuaries Enquiry. These were compared with counts made by us at low water on the adjacent inshore mud- and sandflats. Of 45 comparisons made, 13 differed by less than 25%, 20 by 26–50% and 12 by more than 50%. The high water count exceeded the low water count in 25 comparisons. Counts of Shelduck, Oystercatcher and Knot were the most consistent. Most discrepancies appeared to be due to either an inability to count all areas at low water or by birds, and sometimes roosts, being missed. The correspond...