Scientific Journal of the BirdLife Hungary

A Magyar Madártani és Természetvédelmi Egyesület tudományos folyóirata

Ornis Hungarica. vol.2. (1992) p.1-10.

The method of running-averages in the study of breeding parameters: an example of the Black-birds (Turdus merula)
L. Vanicsek and É. Ludvig

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The seasonal variation of breeding parameters is usually described by calculating the averages of parameters in non-overlapping intervals. This method has two disadvantages: (1) the improper choice of the interval-length makes it impossible to detect either the seasonality or the correlation between parameters in some cases, and (2) even if the interval-length is correct, the detection of seasonality depends on the starting point of the first interval. 'nese problems are discussed in relation to our data collected in an urban Blackbird population during four successive breeding seasons from 1986 to 1989.The method of calculating running-averages is recommended which offsets the above mentioned disadvantages. However this method raises some new problems which are also discussed.