EN
The study was carried out in 7 parks in Poznań in 1987-1990, and in 2 parks from 1979 till 1990. P. Kozłowski's results from Warsaw with large nest-boxes for ducks and owls are included. The study had a threefold objective: - to assess the use made by birds of traditional types of boxes (A, B, D and semi-open P) in an urban environment; - to test new types of nest-boxes, hitherto untried in Poland; - to provide a basis for a comparison with the results of similar studies in Warsaw. In Poznań 2635 nest-boxes x years were inspected (from 145 to 350 annually) -2262 of traditional types (A, B, D and semi-open - type P) and 373 of large types for ducks and owls (Tabs. 1 and 2). The data in Table 3 are taken from 64 inspections of large nest-boxes in Warsaw. Description of 8 types of nest-box were inspected in Poznań: types A and B, built from sandwust-concrete, of sizes: - A - bottom 12 x 12 cm, height from bottom to lower edge of hole 15 cm, diameter of hole 3.3 cm; - В - 13 x 13 cm, 17.5 cm and 4.7 cm respectively; the other types of nest-boxes were made of wood: - D - bottom 15 x 15 cm, height from bottom to lower edge of hole 25 cm, hole diameter 8.5 cm; - P - semi-open, with respective dimensions 10 x 10 cm and 4 cm; - E - 23 x 23 cm, 55 cm, 15 cm; - K - 23 x 23 cm, height 79 cm (no roof); - "Anas" (doghouse) - 60-70 x 40-50 cm, height 40-50 cm. with partition half-way along and an entry hole 25-35 cm in diameter placed towards one and of the longer side; - "Certhia" type imitating a cervice - dimensions 25 x 12 x 3 cm with 3 x 5 cm hole (Fig. 1). During the entire study period in Poznan, 1528 nest-boxes were occupied by birds, i.e. 58% (from 36 to 84% in particular years). Broods of 13 species in nest-boxes were recorded (Tab. 4): Sturnus vulgaris and Passer montanus being the most frequent (684 and 501 occupied nest-boxes respectively). Parus major and Anas platyrhynchos were also numerous (195 and 116 respectively). Only 1 Passer domesticus nest was found in a box in Poznań, which is in stark contrast to the situation in Warsaw, where it is the most numerous species nesting in boxes. Phoenicurus phocnicurus, Ficedula hypoleuca and Erithacus rubecula were also more numerous in Warsaw. These differences were mainly due to the different nature of the parks in which the nest-boxes had been put up in the two cities. Also in contrast to Poznań, Parus caeruleus were more frequent box-nesters than Parus major in Warsaw. A significant factor here was the putting up of A₁ boxes in Warsaw. These have a smaller hole and are therefore preferred by the Parus caeruleus. Percentage occupation in Poznań was highest in A, В and D boxes (71,74 and 72% respectively). Occupation of other types did not exceed 13%, and not a single Certhia sp. took advantage of a „Certhia" nest- box. The large boxes for ducks and owls were rarely occupied. Only the "Anas" (doghouse) boxes and some of the type E nest-boxes located on islands in ponds were quite frequently used by Anas platyrhynchos (113 broods in 4 years).