soils at the nestling sites and at the control sites. Differences showed in metals content in the faeces depended on the localization of colonies. The colony from the former site significantly contributed to the content of Cu, Fe, Zn and Cd in soil. Neither of the rook colonies affected soil Pb levels. The chemical composition of rook faeces reflected the quality of the environment in which rooks feed. Our study findings show that the rook is particularly sensitive to local changes in metals content in the environment.

właściwości gleb dokonano, porównując skład chemiczny gleb na stanowiskach pod gniazdami ptaków i na stanowiskach kontrolnych. Odnotowano statystycznie większą zawartość Fe, Zn i Cd w odchodach ptaków gniazdujących na terenie Siedlce niż w Białej Podlaskiej. Istotny, na zawartość Cu, Fe, Zn, Cd i Pb w glebie, okazał się wpływ siedleckiej kolonii gawronów. Nie wykazano wpływu kolonii gawrona na zmiany zawartości Pb w glebie. Skład chemiczny odchodów jest odzwierciedleniem jakości diety ptaków. Przeprowadzone badania wykaza ły, że gawron jest gatunkiem szczególnie wrażliwym na lokalne zmiany zawartości metali w środowisku.

potential seed dispersal distances. We concentrated on the dispersal of diaspores of ornitochorous species and weeds (called non-ornitochorous) taken probably incidentally during foraging for other edible plant material. The contents of 528 pellets was analysed, 304 were collected at six sites of breeding colonies located in five rural parks and in one park on the city outskirts, and 224 under three winter roosts in the cities. Seeds representing 45 taxa were found, the most important groups among them are: ornitochorous species (10 taxa), non-ornitochorous (27 taxa, mainly weeds and ruderal species) and cereals (4 species). The mean number of seeds varied between 221 and 442 seeds per 100 pellets in the case of breeding colonies, and between 102 and 347 for wintering roosts. Fruits of ornitochorous species are an important element of the diet of the Rook: Cerasus avium and Fragaria sp. during breeding season and Vitis sp., Sorbus aucuparia and Sambucus nigra during winter. Nonornitochorous species are present in pellets in lower numbers and frequencies than ornitochorous ones and they can be divided into two groups: those transported during breeding season (mainly Stellaria media) and those during winter (Setaria sp. and Echinochloa crus-galli). We estimated that the number of non-ornitochorous seeds transported by birds from the biggest observed winter roosts can exceed 400 thousands seeds per month. The value is much lower in the case of the biggest breeding colony: approximately 16 thousands of propagules. We also checked if species found in pellets can germinate in natural conditions under the studied colonies. Viable individuals of 15 nonornitochorous and of one ornitochorous species were found there, and it was observed that disturbances of soil surface promote germination of some analysed species. @eng

birds foraging in three urban parks. The bird counts were conducted in November and December 1988.2003. It was found that the number of wintering Rooks decreased significantly (0.5 fold), populations of Jackdaws and Hooded Crows - increased (4.25 and 3.95 fold, respectively), and no apparent trends were observed for Magpies during this period. Observed trends for Rooks as well as comparisons of limited data gathered earlier in other areas may confirm suggestions about the changing of migration routes of this species.

okazały się tym razem gawrony i kawki.