A Herman Ottó Múzeum Évkönyve 39. (2000)

DUDÁS Miklós: Kelet-cserháti kutatások (Accipitriformes, Falconiformes, Ciconiiformes és Corvidae) az 1989-től 1997-ig terjedő időszakban

Data obtained from survey covering about nine years are summarised for each site. Population size was estimated based on the nests we found and the number of pairs occupying territory. Results are shown in tables and figures. Altogether 83 territory were discovered with 75 twig-nests surveyed. Investigations were carried out on approximately 15 000 hectares. Distribution of territories: one breeding pair per 180 hectares. Populations of prey species deserved particular attention and had to be taken separately, as it basically determined the species composition of the breeding population of the area. Species frequency of occurring birds of prey clearly shows, that species with highest tolerance and adaptivity (cultivation tolerant and favours cultivated areas) dominate on the area. Death caused by 20 kV transmission lines is first on the list of human induced factors influencing population size. On one of the most important feeding grounds („Nagynyilas-dűlő") more traces are crossing. During occasional field visits, under pylons one after another can be found dead Common Buzzards, Kestrels. It would deserve to insulate these critical sections, as it was successfully undertaken on other protected areas of the Great Plain. Actual food resource of the investigated area, the favourable proportion of forest patches suitable for breeding and their relative undisturbedness (moderate tourism, limited forestry activity and hunting, etc.) stabilise the size and actual species composition of the breeding population. Miklós Dudás 524