Methods of bird sociological survey, on the basis of some Tihany communities investigated

Udvardy, Miklós (1947) Methods of bird sociological survey, on the basis of some Tihany communities investigated. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 17. pp. 61-89. ISSN 0365-3005

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Abstract

1. The graphing of the ecological relation between forest and shrubbery types of the area on the basis of qualitative distribution. 2. Calculation of the sociological values from repeated spring surveys of 19 stations (altogether 76 ha) as follows: density of the total population per km-, abundance of the species, individual dominance of the species, dominance-groups. Population studies made in one season and over a limited area are open to much criticism. I present the foregoing, however, for different reasons - for 1946 and for the Tihany peninsula they are accurate, and they give a good basis for methodical reflections, as follows: 3. Palmgren's quadrate method was sufficient in the open woodland and the more open shrubberies. The density of the closed forest and the large quantity of birds therein, on the other hand, caused great difficulties. Here it was necessary to repeat the survey 3-4 times, and to form small stations not more than 2 ha in extent. 4. The aspect of propagation (considering only the first breeding) extends to different epochs in the hibernating residents among the early arriving (beginning of April) and late (at the turn of April-May) summer residents. Therefore we have no standard period in which all members of the population are bound to their territories and thus easily countable. In April some dominant species are still absent; again, by the middle of May the earliest breeders have got their young out of the nests, thereby finishing their localised season. All these relations are explained by the phaenological spectra 5. The nesting and feeding territory is not the same place for the greater part of the species of the shrubby pasture and forest. In the sociological characterising of these we must express, with a special relative figure, that the species nests or feed, or both, locally, in the community individual recorded, or generally, that is, in the whole community. Because of these species I could not employ the term character- species ("Karakterart" of the botanists) nor the degrees of Fidelity (exclusiveness). 6. This method is not suitable for calculating degrees of constancy. The correct establishment of constancy and frequency must take place in connection with the time factor - and attempts are being made in this direction - because the role of the bird is periodical in the different biotic communities.

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