The frequency method in studying habitat preferences of common forest birds

This paper presents the results of a study on the habitat preferences of selected species of the bird community in the Morgi Forest, the Kolbuszowa Forest Division (SE Poland), with the use of the point-stand bird census method. The aim of the study was to test the effectiveness of the method in determining the frequency of colonisation of stands with different habitat parameters by the most abundant bird species. In 270 tree stands of a forest complex with diverse habitats, a bird census was carried out with four counts per each stand. Next, a list of the tree stands and the bird species recorded in the stands was compiled. The stands were divided into categories according to the forest habitat type, dominant species and age class. In the next step, the occurrence frequency of the most abundant bird species was calculated for each stand category. Among the analysed species, the majority showed a positive correlation between the frequency of occurrence and habitat fertility. The influence of the dominant stand species on the occurrence frequency of bird species was largely driven by habitat fertility. The lowest average frequency of the identified avian species was found in stands dominated by pine Pinus sylvestris, birch Betula sp. and black alder Alnus glutinosa. There was generally a positive relationship between age class and the bird community parameters. It is concluded that the point-stand method of bird census provides informative results for research on the habitat selectivity of bird populations.