TRENDS OF BIRD POPULATIONS IN A MANAGED LOWLAND RIVERINE ECOSYSTEM

Breeding birds along the lower reaches of the River Dyje, Czech Republ ic, were surveyed from 1986 to 1995. Overall, 93 avian species were re corded: 73 in woodland habitats (WL: floodplain forest) and 86 in open land habitats (OL: riparian ecotone, farmland); 6 spp. were dominant i n WL (Fringilla coelebs, Ficedula albicollis, Sylvia atricapilla, Erit hacus rubecula, Phylloscopus collybita, Sitta europea) but only 2 spp. in OL (Acrocephalus palustris, Emberiza citrinella). Bird abundance, density and biomass were higher in WL, whereas species diversity was h igher in OL. Within the census period, an increase was detected in pop ulations of Columba palumbus, Streptopelia turtur, Cuculus canorus, St rix aluco, Picus viridis, Dendrocopos major Jynx torquilla, Alauda arv ensis, Luscinia megarhynchos, Sylvia atricapilla, Parus caeruleus, Rem iz pendulinus, Oriolus oriolus, Lanius collurio, Carduelis chloris and Emberiza citrinella. Declining species were Delichon urbica, Sylvia c ommunis and Corvus corone. A concave trend was found in Phasianus colc hicus, Gallinula chloropus, Hirundo rustica, Riparia riparia, Motacill a alba, Troglodytes troglodytes, Aegithalos caudatus, Passer montanus, Serinus serinus, Carduelis carduelis, and a convex trend in Streptope lia decaocto, Apus apus, Sylvia nisoria and Emberiza schoeniclus. In c omparison to the bird fauna a century ago (1893-1905), local populatio ns of a number of species disappeared (Anas crecca, A. acuta, Falco na umanni, Coturnix coturnix, Tringa tetanus, Scolopax rusticola, Caprimu lgus europaeus, Coracias garrulus, Lanius minor L. senator Miliaria ca landra) or decreased substantially (e.g., Ixobrychus minutus, Anas cly peata, A. strepera, A. querquedula, Perdix perdix, Crex crex, Vanellus vanellus, Columba cenas, Tyto alba, Athene noctua, Upupa epops, Galer ida cristata, Motacilla flava, Phoenicurus phoenicurus, Acrocephalus s cirpaceus, A. arundinaceus, Garrulus glandarius, Corvus monedula). Som e species have appeared as new (e.g., Streptopelia decaocto, Dendrocop os syriacus, Prunella modularis, Turdus viscivorus, Remit pendulinus, Lanius excubitor) or increased (e.g., Saxicola torquata).