POPULATIONDYNAMICS - MONITORING POPULATION DYNAMICS 1961-1990 OF COMMON LEAF WARBLERS (PHYLLOSCOPUS SP.) AT SOME CENTRAL EUROPEAN BIRD RINGING STATIONS Przemyslaw Busse and Irina Marova ABSTRACT Busse P., Marova 1. 1973. Population dynamics 1961-1990 of common Leaf Warblers (Phylloscopus sp.) at some Central European bird ringing stations. Ring 15, 1-2: 61-80. The paper is intended to give more general picture of population dynamics of Willow Warbler, Chiffchaff and Wood Warbler on bigger areas and to point at some problems arising when such data are evaluated. It contains evaluation of monitoring the numbers of migrating birds by autumn trapping results at 13 bird ringing stations dispersed throughout the central and northern Europe. The longest data series cover 30 years (1961-1990). Evaluation and presentation of data are based on methods discussed earlier (Busse 1990). Studied species are not equally represented in the station catches and average numbers per season and per one station were: 460.0 (Willow Warbler), 136.6 (Chiffchaff) and 14.4 (Wood Warbler). Yearly fluctuations around smoothed (by five year moving average) number dynamics curves much are differentiated (CF values examined) at separate stations. When data pooled for species at six main stations were studied Willow Warbler and Chiffchaff show lower values (CF = 5.12 and 5.09 respectively) than Wood Warbler (9.58); these values are much lower than averages for stations. The population trends at the stations were differentiated with examples of both decrease and increase of numbers. However, regression coefficient values for long-tenn series of pooled data were all negative (Willow Warbler - R ~ -1.90, Chiffchaff - -2.45, Wood Warbler - -3.21) and statistically highly significant. Population dynamics curves for pooled data were positively correlated between Willow Warbler and Chiffchaff as well as between Willow Warbler and Wood Warbler (highly! significant), but correlation between Chiffchaff and Wood Warbler was low and not significant. At the level of,separate stations correlation were differentiated so much that further studies of the problem are necessary. Evaluation of migration monitoring data from number of stations covering larger territory and few species simultaneously points at number of new problems connected with interpretation of the results. These are interpretation of differences in numbers of birds caught at the stations, of the level of yearly fluctuations at stations and the pooled data, of correlation of number dynamics of the species between stations, and of correlations between species population dynamics. P. Busse, Bird Migration Research Station, University of Gdansk, Przebendowo, 84-210 Choczewo, Poland 1. Marova, Dept. of Zoology, Moscow State University, Lenin Hills, 119899 Moscow, Russia Number of papers evaluating the migration counts conducted at single or few bird ringing stations were published since this method of monitoring was accepted (Lindholm et al. 1983, Busse 1984, Baumanis and Rute 1986, Berthold et al. 1986, Busse and Cofta 1986, Peterson and Hedenstrom 1986, Svensson et al. 1986, Rab01and