A Debreceni Déri Múzeum Évkönyve 1986 (Debrecen, 1987)

Természettudomány - Juhász, Lajos–Bozsko, Szvetlana: The Ornithofauna of Debrecen II. Synecological Analysis

count than Passer domesticus. These, with the species Streptopelia decaocto, which populates the area evenly, and with the long-staying wintering guests (e.g. Corvus frugilegus, Bombycilla garrulus, Carduelis spinus) and the already arriving migratory species (Hirundo rustica, Phoenicurus ochruros, Sylvia curruca, Sturnus vulgaris) form a heterogeneous bird community. In the garden city biotope there are 30 nesting species. Thus, nearly all the 32 species observed in the nesting period are present here as breeders. Characteristic, in addition to the common species, are Upupa epops, Galerida cristata, Phoenicuros ochruros, Sylvia curruca, Sturnus vulgaris. The conditions of dominance show a typical levelled distribution: 3 species are eudominant (summa D: 49.78%) 1 species is dominant (summa D: 7.43%) 7 species are subdominant (summa D: 27.07%) 10 species are accessorical (summa D: 7.86%) 11 species are rare (summa D: 7.86%) In the autumn season repeated rearrangement of species and changes in dominance and abundance can be observed. Apart from the permanent ED species, frequently appear as D wanderers Parus major, (4.54 pairs/10 ha), Corvus frugilegus (16.59 pairs/10 ha), Sturnus vulgaris, which feed on fruit (4.50 pairs/10 ha), and the early arriving Carduelis spinus (4.54 pairs/10 ha). In cold winters the whole spectrum of the wintering guests that come to the town can be registered in the garden city, and what is more some species infiltrate into this biotope in largest numbers (e.g. Carduelis cannabina, Carduelis chloris, Carduelis spinus, Fringilla montifringilla). 6. Small urban parks (plot size: 2.5 ha). These are plots of a few hectares occupying a special state in Debrecen. Owing to their significant vegetation and isle-like distribution in the town, they play an outstanding role in the development of the urban ornithocenose. They facilitate the longer stay and accumulation of the species deeply penetrating into the town. The small town parks provide natural replacement for the city ornithofauna, and also decrease the differentiation of the bird community of the particular districts of the town. On the annual level 54 species were demonstrated in characteristic dominance distribution (Table 6). It is in the spring period that the greatest richness in species can be observed (38 species) and nearly maximum abundance (57.0 pairs/ha). The number of transitory species is considerable, thus e.g. three Phylloscopus species, Regulus regulus, Luscinua megarchynhos. We have succeeded in registaring such rare species as Ficedula hypoleuca and Turdus torquatus. The relatively high abundance and dominance values of the seed-eating song-birds (Carduelis carduelis, Carduelis chloris, Fringilla coelebs) is striking already in the spring season. In the nesting period the park avifauna gets somewhat poorer, however the 18 species proven to be actually nesting ones represent a real value for the town's ornithofauna. Leaving the two Passer species out of consideration the characteristic species of the small parks is Turdus merula (4.8 pairs/ha.) Significant are the populations of the members of the family Siviidae and the Fringillidae species. The varied vegetation, especially the pines, low-growing thuyas, bushes provide these species with favourable conditions. The small parks with the surrounding buildings are favourable biotopes for the Passer species and Streptopelia decaocto. The mean abundance reaches 46.6 pairs/ha in breeding season. The autumn season brings about the reduction of mean abundance (40 pairs/ha), and 47