DIJK A VAN, F HUSTINGS, A BOELE, K KOFFIJBERG, D ZOETEBIER & CL PLATE (2010) Rare and colonial breeding birds in The Netherlands in 2006-2007. LIMOSA 83 (1): 1-20.

National censuses of colonial and rare breeding birds in The Netherlands have been carried out from 1992 onwards (and earlier for some species). The project focuses on 17 colonial breeding birds and about 80 rare breeders (Table 1) and is part of a governmental ecological monitoring scheme. National co-ordination is carried out by SOVON Dutch Centre for Field Ornithology, in close cooperation with Statistics Netherlands (trend analyses). In the Wadden Sea the counts are part of the trilateral TMAP monitoring program. For some species the data are mainly derived from (annual) species-specific surveys, e.g. White Stork Ciconia ciconia, Eurasian Spoonbill Platalea leucorodia, Montagu's Harrier Circus pygargus, Peregrine Falcon Falco pelegrinus, Corn Crake Crex crex, Little Owl Athene noctua, Barn Owl Tyto alba, European Nightjar Caprimulgus europaeus (2007 only) and Redbacked Shrike Lanius collurio. Other rare breeding birds are surveyed annually at least in the core breeding areas, including all Natura 2000 sites. Colonial breeding birds are usually covered fully. Fieldwork is highly standardised and mostly carried out by dedicated amateur birdwachters and staff of nature reserves. Trend analyses are carried out with TRIM and baseline results are published in annual reports and on www.sovon.nl.
      This paper summarises the results for 2006 and 2007. Numbers, estimates, details of coverage and an assessment of trends are listed in Table 1. Highlights among rare breeding birds in 2006-2007 included records of Cattle Egret Bubulcus ibis (2006, second ever), Whooper Swan Cygnus cygnus (2006-07, first breeding 2005), White-tailed Eagle Halieetus albicilla (2006-07, first records, both years one young fledged, Oostvaarders - plassen), Common Crane Grus grus (three pairs of which two successful, Drenthe), Black-legged Kittiwake Rissa tridactyla (40 pairs in 2006 on three offshore platforms in the North Sea), White-winged Tern Chlidonias leucopterus (first breeding of four pure pairs in 2007, following an influx in May), European Bee-eater Merops apiaster (1-3 pairs) and Paddyfield Warbler Acrocephalus agricola (2007 successful pair on Vlieland, first breeding record). Previous increases in Little Egret Egretta garzetta, Eurasian Spoonbill, Peregrine Falcon, Mediterranean Gull Larus melanocephalus, European Nightjar, Common Kingfisher Alcedo atthis, Middle-spotted Woodpecker Dendrocopos medius, Grey Wagtail Motacilla cinerea, Cetti's Warbler Cettia cetti and Zitting Cisticola Cisticola juncidis continued in 2006-07. Also many goose species thrived, but total population sizes were not assessed in these species. Corn Crake experienced a peak year in 2007 after three years of low abundance in 2004-2006. Little Tern Sternula albifrons reached highest numbers in the past decades. Barn Owl had its best breeding year in nearly 50 years (3300 pairs in 2007), with lots of second clutches and high success.
      Previously expanding Great White Egrets Casme riodius albus experienced a sharp decline in their core breeding area in the Oostvaardersplassen (143 pairs in 2006, 43 in 2007) due to drought in the breeding colony. Species with continuing long term declines include Hen Harrier Circus cyaneus (41 pairs remaining on Wadden Sea islands in 2007), Black Grouse Tetrao tetrix (one site with 15-23 males, re-introduction at second site in 2007/08), Kentish Plover Charadrius alexandrinus, Ruff Philomachus pugnax (nearly extinct), Black-headed Gull Chroicocephalus ridibundus (decline now spreading to Wadden Sea), Short-eared Owl Asio flammeus (all-time low), Eurasian Wryneck Jynx torquilla (a few tens at most), Crested Lark Galerida cristata (all-time low), Tawny Pipit Anthus campestris (one territory in 2007, probably not breeding), Northern Wheatear Oenanthe oenanthe, Fieldfare Turdus pilaris, Great Reed Warbler Acrocephalus arundinaceus (2006 lowest number since 1990) and Penduline Tit Remiz pendulinus. Great Grey Shrike Lanius excubitor and Ortolan Bunting Emberiza hortulana must be considered extinct. Corn Bunting Emberiza calandra balances on the verge of extinction. Pied Avocet Recurvirostra avosetta stabilised, but its population has declined with 31% since 2000. Declines were reported for Rook Corvus frugilegus, a species increasingly faced with disturbance of breeding colonies in urban areas.

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