DIJK AJ VAN, KLEEFSTRA R, ZOETEBIER D & MEIJER R (2000) Rare and colonial breeding birds in the Netherlands in 1997. LIMOSA 73 (2): 53-66.

This paper reviews the status of colonial and rare breeding bird species in The Netherlands in 1997, based on annual surveys of all colonies and sites with rare breeding birds. Full details on the 1997 census are given in van Dijk et al. (1999a). Table 1 lists all species recorded , the number of breeding pairs, estimate of the national population and the most recent previous estimate. Breeding conditions in 1997 were especially influenced by severe winter weather in December 1996 and January 1997. However, contrary to the previous harsh winter in 1995/96, the cold-spell in 1996/97 was relatively short, followed by very mild weather after Mid-January. Besides, low precipitation rates caused low water tables in wetlands and marsh areas, affecting the settlement of some wetlandbreeding species like Black-necked Grebe.

Despite the second severe winter in a row, Grey Heron numbers (9600 pairs) decreased by only 4% on a nationallevel (numbers have dropped by 30% since 1995). Common Kingfisher numbers feil by at least 50% to a very low level of only 35-50 breeding pairs, rep resenting a 90% decline in numbers since 1995. Grey Wagtail numbers decreased markedly (-30%), especially when considering the relatively small decrease after the more prolonged severe 1995/96 winter. Great Bittern, who se numbers suffe red a 30% decrease in 1995/96, stabilised at 140-160 pairs. As mentioned before, Black-necked Grebe suffered from dry habitat conditions (195-215 pairs). However, May and June were wet and offered favourable conditions for Spotted Crake (195-245) and Corn Crake (260-275 calling males; the highest number since the 980s) and perhaps Little Crake and Baillon's Crake as weil (8 and 9 records, respectively, though poorly documented). The 1997 breeding season showed high numbers of Eurasian Spoonbil! (1138 pairs; new record), Redcrested Pochard (80-95) , Mediterranean (376) and Lesser Black-backed Gul! (57 200), Eurasian Penduline Tit (205-230) and Red-backed Shrike (225-245). Greater Whitefronted Goose (100-130) , Barnacle Goose (220-250) and Greater Canada Goose (200-230) flourished as well. Breeding numbers in Purple Heron (300), Pied Avocet (7100), most tern species, Sand Martin (18500), Rook (58 000) and Tawny Pipit (40-55) were more or less stabie. Lowest-ever numbers were found in Ruff (135-185; against 6000 in the 1950s), Short-eared Owl (45-50), Crested Lark (6080), Whinchat (360-420), Great Reed Warbier (250-275) and Ortolan Bunting (2 territories, no breeding evidence).

Several rare breeding species occurred in 1997, including Liltle White Egret (3 pairs), Black-crowned Night Heron (perhaps 4), Great Black-backed Gul! (8), Middle Spotted Woodpecker (9, nearly all in the utmost SE of the country), Whiskered Tern (first breeding case since the 1960s), Hoopoe (1), Eurasian Treecreeper (60-70, nearly all in Limburg, SE-Netherlands) and Common Rosefinch (45-55, manly at the Wadden Isles and elsewhere along the North Sea coast). A pair of House Crows, present since 1994, produced one young.

Special research on Bearded Reedling revealed some 1800-2000 breeding pairs, 90% of which breed in the core areas Oostvaardersplassen (Flevopolders), Lauwersmeer and along the coast of Lake Ijsselmeer. Areas with vast old reedbeds held the highest densities (mean density 4.0 pair/10 ha).

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