Etho-ecological study of the singing activity of the Blue Tit (Parus caeruleus), Great Tit (Parus major) and Chaffinch (Fringilla coelebs).

The main objective of this study was to determine the extent of influence that a large city's ecological conditions have on the singing behaviour of urbanised birds. The singing activity of selected bird species was examined using the ''animal focus sampling'' method. The observations were carried out from the beginning of March to the beginning of June 1995 in a 10 ha inner city park, the Westpark (WP) in Dortmund (NRW, Germany). An area of equal size in a forest south of Dortmund, the Niederhofer Wald (NW) was chosen as a control area. In the Westpark the Blue Tit, Great Tit and Chaffinch started to sing significantly earlier in the morning than in the control area. This difference could be due to the artificial lighting of the park at night as well as the noise of traffic. There was no difference in the three species' singing activities between the two areas, but there were differences in the temporal pattern of the Chaffinch's morning singing activity in comparison of the two areas. In the Niederhofer Wald the Chaffinch was almost equally active at all times whereas it showed a pattern similar to the Tit's ''dawn chorus'' in the Westpark. Food supply, distribution and predictability within the two areas are discussed as causes for this difference. However, the negative correlation between singing activity and the frequency of pedestrians crossing the birds' territories may also play a role. In the Westpark, a correlation between the Chaffinch's singing activity and the frequency of passing pedestrians was noted. The more people crossed the focus animal's territory, the less its singing activity and the more frequently ''pinks'' occurred. Thus, pedestrians do indeed disturb the Chaffinch which reacts with a change of singing behaviour.