SEGREGATION OF DIET IN WATER PIPIT (ANTHUS-SPINOLETTA) IN MEADOW PIPIT (ANTHUS-PRATENSIS) NESTLINGS IN AN AREA DAMAGED BY AIR-POLLUTION

Analysis during the breeding seasons between 1985 and 1991 of the diet ary items offered to water pipit (Anthus spinoletta) and meadow pipit (Anthus pratensis) nestlings in the Jeseniky Mountains, an area damage d by air pollutions, revealed an unexpected differences between the tw o species. The diet of water pipit nestlings contained significantly m ore Diptera (36.5 : 13.5 %) and significantly less Araneida (1.7 : 4.0 %), Gastropoda (0.1 : 3.4 %) and Homoptera (21.6 : 38.2 %). Also the average body length of prey of water pipit was significantly bigger (8 .3 : 6.8 mm). Water pipit hunted more prey during periods of unfavoura ble climate, used rather different foraging sites and almost did not h unt Gastropoda, a significant resource of calcium. Foraging strategies of both the species were probably different.