DAEMEN B, HUSTING F, LENSINK R & VERSTRAEL T (1991) Point-Transect-Counts of wintering birds in 1986 / 1987 - 1988 / 1989. LIMOSA 64 (2): 50-60.

This paper summarizes results of Point-Transect-Counts in The Netherlands during the winters of 1986 / 1987 1988 / 1989. The project, intended to monitor populations of wintering birds, started on a modest scale in 1978. Counts of selected routes with 20 fixed counting-points are held in periods of 16-17 days in mid-November, late December and mid-February (count in August not discussed here). In the winters of 1986/87-1988/89 the number of routes in November was 319, 330 and 334, in December 384, 418 and 405 and in February 332, 350 and 307. The percentages of paired routes between years (70-85%) and within a winter season (85-95%) (fig. I) were statistically satisfactory, as was the spatial distribution of routes over the country (fig. 2). The weather during the three consecutive winters was highly variable. The winter of 1986/87 was the last in a series of three severe winters, whereas the 1987/88 and 1988/89 winters were unusually mild (fig. 3). Total numbers of birds counted were, generally speaking, smaller than in the early 1980s. In December 1988, however, large numbers of birds were recorded, due to high temperatures in The Netherlands and a short cold spell in Eastern and Northern Europe (fig. 4). The most numerous species during these winters were White-fronted Goose (maximum number 180 000), Black-headed Gull (max. 162 000), Wigeon (max. 124 000), Lapwing (max. 122000), Starling (max. 90000) and Mallard (max. 89 000). Carrion Crow, Great Tit, Magpie and Blackbird were most widely distributed; they were present at 95-100% of all routes. The groups of residents, residents/ winter visitors and winter visitors showed similar fluctuations each winter, with the exception of February 1988 (fig. 5). The abundance of many species in that month was probably caused by a combination of territorial behaviour in residents (increasing detectability) and early migration to the breeding grounds of migrant species. Both phenomena were triggered by unusually mild weather. Tab. 1 demonstrates the winter-fluctuations of some species (numbers in December set at index 100). Rather many species had their lowest index since 1980 in the winter of 1986/87, probably as a result of three cold winters in succession. A relatively large proportion of species had their highest index in 1987/88 and 1988/89, indicating that losses during the previous severe winters were overcome soon (fig. 6). In fig. 7 the annual December- indices are presented for groups of species with the same migratory habits. December-indices of single species can be found in Appendix 1. Long-term trends in a few species are given in fig. 8. Kestrel and Partridge have clearly declined in the 1980s, while Stock Dove populations have increased.' The increase of the Collared Dove has turned into a decrease since about 1984. The numbers of Siskin and Brambling fluctuate considerably. Although the project was not intended to produce distribution maps of species, the counting method and the rather even distribution of routes over the country allows for interesting di~tribution-datato be collected for some species. The recent increase in wintering numbers of Kestrel and Wren, corresponding with results of breeding surveys, is illustrated in fig. 9. ##### Grey Heron Ardea cinerea Eurasian Nuthatch Sitta europaea Short-toed Treecreeper Certhia brachydactyla Eurasian Magpie Pica pica Common Pheasant Phasianus colchicus Yellowhammer Emberiza citrinella Marsh Tit Poecile palustris Eurasian Bullfinch Pyrrhula pyrrhula European Green Woodpecker Picus viridis Great Spotted Woodpecker Dendrocopos major Northern Goshawk Accipiter gentilis House Sparrow Passer domesticus Western Jackdaw Coloeus monedula Mute Swan Cygnus olor Great Tit Parus major Willow Tit Poecile montanus Grey Partridge Perdix perdix Blue Tit Cyanistes caeruleus Eurasian Tree Sparrow Passer montanus Rook Corvus frugilegus Long-tailed Tit Aegithalos caudatus Common Kestrel Falco tinnunculus Eurasian Collared Dove Streptopelia decaocto Eurasian Jay Garrulus glandarius Winter Wren Troglodytes troglodytes Carrion Crow Corvus corone Coal Tit Periparus ater Black Woodpecker Dryocopus martius Common Buzzard Buteo buteo Little Grebe Tachybaptus ruficollis Great Crested Grebe Podiceps cristatus Goldcrest Regulus regulus European Greenfinch Carduelis chloris Mistle Thrush Turdus viscivorus Dunnock Prunella modularis Stock Dove Columba oenas Common Wood Pigeon Columba palumbus Lesser Black-backed Gull Larus fuscus Black-headed Gull Chroicocephalus ridibundus Tufted Duck Aythya fuligula Eurasian Coot Fulica atra Common Blackbird Turdus merula Common Reed Bunting Emberiza schoeniclus European Robin Erithacus rubecula Eurasian Sparrowhawk Accipiter nisus Common Starling Sturnus vulgaris Common Gull Larus canus canus Common Pochard Aythya ferina Common Chaffinch Fringilla coelebs Common Moorhen Gallinula chloropus Mallard Anas platyrhynchos Eurasian Curlew Numenius arquata Song Thrush Turdus philomelos European Herring Gull Larus argentatus Hen Harrier Circus cyaneus Common Goldeneye Bucephala clangula Great Black-backed Gull Larus marinus Goosander Mergus merganser Brambling Fringilla montifringilla Bewick's Swan Cygnus bewickii Greater White-fronted Goose Anser albifrons Redwing Turdus iliacus Fieldfare Turdus pilaris Smew Mergellus albellus Taiga Bean Goose Anser fabalis Eurasian Siskin Carduelis spinus Eurasian Wigeon Anas penelope Northern Lapwing Vanellus vanellus Eurasian Skylark Alauda arvensis

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