EARLY STAGES OF THE NESTING PERIOD OF HOLLOW-NESTING BIRDS UNDER CONDITIONS OF INDUSTRIAL-POLLUTION

The influence of copper-smelting plant discharges on early stages of t he nesting period of the great tit, coal tit, and pied flycatcher was studied. The species-dependence of toxic load, defined by the level of heavy metal in the alimentary canal (a. c.) and feces of the birds is revealed. The egg volume reliably decreased in the direction of the p ollution gradient in all species. The complete clutch size, successful ness of incubation, and amount of newly-hatched nestlings decreased in all species, but reliably only for the pied flycatcher, which was exp osed to the largest toxic load. With an increase of the load on the bi rds, the variability of many reproductive parameters also rose, possib ly indicating unfavorable conditions of the studied bird group.