KATE GCBT (1952) The Breeding-Birds of the "Oosterpolder" 1951 and 1952. LIMOSA 25 (1): 1-11.

In the first part of this article the change of the breeding-bird-life along the southern border of the chief mouth of river IJssel is discussed. In consequence of the dumping of ground, left over by the diverting of the rivermouths in connection with the works of the "Noordoostpolder" (see map 1) Ringed Plover, Little Ringed Plover, Kentish Plover, Avocet, Common Tern and Little Tern settled here. Later on they were driven away again as the area for the greater part was occupied as storage ground and working basis for the new reclaiming works. However they got a new home as along the shore peat-soil was dumped. acquired from the former sea-bottom during the works for the new polder (see map 2, "Vossenwaard" and fig, 3-6).
The second part deals with the birds of the future "Oosterpolder" itself. After the "Wieringermeer" (20.000 hectares, ready in 1930) and the "Noordoostpolder" (48,000 hectares, ready in 1942), the works for the third Polder, the "Oosterpolder" (54,000 hectares) were started at 3 places, indicated on map 1 as "Perceel P, Q and R", at the same hme in June 1950, In March 1951 a beginning was made at a fourth point ("Perceel S" : see also map 1) and finally in the spring of 1952 at a fifth place ("PerceeI R"'), Before long most probably parcel T will also be taken in hand; this will join on to parcel S in a NE direction (see map 1), Already during the breeding-season 1951 at least 3 species settled on a small beach along the Western side! of the new dam in "Perceel Roo (see fig, 7): Little Ringed Plover, Common Tern and Little Tern. In 1952 the number of breeding species increased strongly, On this little beach and a second one along the curve of the dam (see map 2) and also on the dam itself with the other artificial works belonging to it, 16 species were found: ReedBunting (lor 2 pairs), Sky-Lark (probably some pairs), Blue-headed Wagtail (ditto), White Wagtail (I pair, "Perceel pool, Reed-Warbler (settlement of 1 or 2 pairs late in the season - July - in the greatly enlarged reeds on the first small beach). MalIard (2 pairs), Oyster-catcher (I pair), Ringed Plover (at least 1 pair), Little Ringed Plover (at least 10 pairs), Kentish Plover (at least 14 pairs), Lapwing (probably 1 pair), Redshank (probably 2 pairs) , Avocet (possibly 1 pair), Common Tern (2 colonies of each about 15 pairs), Little Tern (I pair, nesting in company with some Little and Kentish Plovers on a storage ground with an upper layer of ground blast-furnace slags: see fig. 8 and 9) and Black-headed Gul1 (possibly 1 pair).

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