DIJK A VAN, HUSTINGS F, KOFFIJBERG K, TURNHOUT C VAN, WEIDE M VAN DER, ZOETEBIER D & PLATE C (2007) Rare and collonial breeding birds in The Netherlands in 2003-05. LIMOSA 80 (2): 49-67.

From 1990 onwards, a national census of rare and colonial breeding birds in the Netherlands has been carried out annually (some species earlier data available). These surveys include 17 species of colonial breeding birds and 78 rare breeders (Tab. 1) and are part of a national governmental monitoring scheme, co-ordinated by SOVON Dutch Centre for Field Ornithology. Censuses in the Wadden Sea are carried out in the framework of the trilateralmonitoring programme TMAP, togetherwith partners in Germany and Denmark. Fieldwork is mainly conducted by dedicated volunteers, staff of site-managers and nature conservation agencies as well as a number of institutes. Both fieldwork and data processing are standardised according to guidelines in a special manual. Data are transferred online at www.sovon.nl or by standardised data sheets. Coverage varies among species, but in general all key-breeding areas, including all Natura 2000 sites, are covered annually. For some species (e.g. White Stork, Eurasian Spoonbill, Montagu's Harrier, Black Grouse, Corn Crake, Barn Owl) species-specific surveys delivermost of the data. Furthermore, a special census of breeding goose populations was carried out in 2005. Trend analyses are carried out with the common TRIM package and baseline results are reported in annual reports. This paper summarises data from 2003-2005. Numbers, estimates, details on coverage and an assessment of trends are given in Tab. 1. For a selection of species, trends in annual (counted) numbers are shown (Fig. 3, 4, 5, 7). Additionally, a comparison is made between breeding distribution in 1998-2000 (new breeding bird atlas) and 2003-05 (this paper) to reveal some of the changes in distribution that have occurred recently in some species (Fig. 2, 6, 8-12).

All three breeding seasons were preceeded by normal to mild winters (note, however, severe but short cold spells by the end of winter in 2004 and 2005). Temperatures were generally well above long-term average, confirming the global tendency for warmer winters. Spring 2003 was dry whereas July 2004 and 2005 were (extremely) wet (Fig. 1). Highlights in rare breeding birds in 2003-2005 included first breeding of Whooper Swan (2005, province Drenthe; failed), annual breeding of Common Crane (2 successful pairs in Drenthe, additional records of individuals during the breeding season), a small influx of Baillon's Crake (10 singing males in 2005), first breeding Gull-billed Tern since 1958 (2005 Wadden Sea; failed), successful breeding of European Bee-eater (3 pairs in Zuid-Holland in 2005), 2nd breeding record for Trush Nightingale (nest in 2005 in Flevoland) and first breeding of Greenish Warbler (2003, Island of Schiermonnikoog). Besides, breeding of Black-legged Kittywake at a platform on the Dutch continental shelf, NNW off the Island of Texel (reported since 2000) could be confirmed in 2004. Osprey was observed several times during the breeding season, but nesting could not be confirmed. Earlier increases reported for Little Egret, Great Egret, Eurasian Spoonbill, Barnacle Goose (6000 pairs in 2005), Greater Canada Goose, Red-crested Pochard, Peregrine Falcon, Greater Black-backed Gull, Eurasian Eagle Owl and European Nightjar continued in 2003-2005, partly also co-inciding with an extension in breeding range. Also Middle Spotted Woodpecker expanded its breeding range outside the stronghold in the extreme south of Limburg. Especially Great Bittern, Common Kingfisher and Grey Wagtail benefited from the lack of severe winters since 1997/98 and boomed in 2003-2005.

Contary to increases in these species, a number of habitat specialists declined sharply and partly balance on the verge of extinction. These include Eurasian Wryneck, Crested Lark, Tawny Pipit (no breeding pairs in 2003-05), Great Grey Shrike (no breeding pairs), Ortolan Bunting (virtually extinct) and Corn Bunting. Hen Harrier and Short-eared Owl currently experience declines that might well bring them on the verge of extinction in near future. Both species have contracted their breeding range to a few islands in the Wadden Sea and have become vulnerable. Also Northern Wheatear has suffered major losses and has deserted many breeding sites in the coastal dunes in Zuid-Holland and interior parts of the country. Specific research in 2005 showed that a large number of breeding pairs (in 2005 48% of 199 pairs monitored) failed to reproduce. Earlier declines reported for Ruff, Black-headed Gull, Arctic Tern, Whinchat, Great Reed Warbler, Penduline Tit and Common Rosefinch continued after 2003. In Eurasian Penduline Tit and Common Rosefinch, this trend represents a retreat from an expansion observed in the 1980s and 1990s. Recently, also population size of Pied Avocet along the Wadden Sea coast (mainly northern coast of Groningen and Dollard) has gone down. In a number of colonial breeding birds a tendency for more but smaller colonies has been observed. This trend has been recorded in Great Cormo - rant, Grey Heron and Rook. In Great Cormorant, this tendency was enhanced by the creation of large artificial islands in Lake IJsselmeer. These islands also attracted Great Ringed Plover, Common Tern (one island with 3700 breeding pairs representing the largest colony in the country), Mediterranean Gull and occasional breeders of Kentish Plover and Little Tern.

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