Pleisterende Regenwulpen Numenius phaeopus in Drenthe in 1980-95
Drentse vogels , Volume 10 - Issue 1 p. 27- 36
Staging Whimbrels are widespread in the province of Drenthe, mainly occurring east of the line Dedemsvaart-Hoogezand. Birds are present from March (very scarce) through October (ditto), showing distinct peaks in April-May and July (Fig. 1). Median dates of presence in spring in 1980-90 and 1991-95 were respectively 29 and 28 April; in summer it was 17 July in both periods. Concentrations were recorded at or near roosts, such as Bunnerveen, Fochteloerveen, Doldersummerveld, Dwingelose Heide and Nijeveen. Staging numbers have declined since the mid-1970s, both in spring and summer (Table 1). This was mainly caused by a shift in foraging and roosting sites from Drenthe into Friesland, i.e. some 20-50 km to the west of Drenthe. Flock size of staging birds peaked in April, May and July and averaged 21 birds for the entire period. Many roosts are known throughout Drenthe, many of which were used irregularly (depending on suitablity with respect to water level and predation). Roost assemblages in Drenthe have become increasingly smaller during 1975-95, as exemplified by the maximal roost size in 1975-79 (10,112 birds), 1980-85 (2700), 1986-90 (1300) and 1991-95 (574).
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