THE CAUSES OF THE MORTALITY OF EGGS AND NESTLINGS OF PASSER SPP

In the world-wide literature the role of predators and food shortage a re considered as responsible for mortality of eggs and nestlings. In s ynantropic altricial hole-nestling birds such as sparrows Passe, domes ticus (L.) and Passer montanus (L.) the predation plays unimportant ro le and in spite of this, mortality of eggs and nestlings can exceeded 50%. The role of microorganisms, heavy metals, pesticides and food sho rtage were investigated as possible causes of embryo and nestling deat hs. About 70% of eggs that not hatched were infested with such pathoge ns as Escherichia coil, Staphylococcus epidermitis and several, more r arely occurring others. Considerable percentage of nestlings died due to pathogenic impact of such factors as Escherichia coli, Isospora lac azei, Candida spp., heavy metals and pesticides. As one effect of such interaction, the level of sublethal doses of heavy metals and pestici des are much lower that reported in the literature.