VEN J VAN DER (1962) The heronries of the Grey Heron Ardea cinerea in the Netherlands in 1956 and 1961 Ardea cinerea. LIMOSA 35 (3): 266-269.

In 1956 a census of the heronries of the Common Heron was made to compare the number of breeding pairs in that year with those of former censusses 1925126, 1935/37 and 1949. The results are given in table 1 (per province) and in the accompanying map. The number of breeding pairs has increased slightly; 33 colonies still present in 1949: did not exist any longer in 1956, but 48 new, though generally smaller colonies were established. In 14 colonies (among which some important ones) an increase was established from 521 nests in 1956 to 804 in 1961. The total number of breeding pairs in 1961 therefore is estimated well over 5000. Grey Heron Ardea cinerea

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