LOCAL SURVIVAL RATES OF THE PIED FLYCATCHERS (FICEDULA-HYPOLEUCA) ANDTHE GREAT TITS (PARUS-MAJOR) IN AN AIR-POLLUTION GRADIENT

We studied the local survival of pied flycatcher (Ficedula hypoleuca) and great tit (Parus major) females under heavy air pollution stress. Females were trapped from three distance zones around a copper smelter in the town of Harjavalta, southwestern Finland, from 1991 to 1995. T he main pollutants in this area are heavy metals (Cu, Ni, Zn, Pb) and sulphuric oxides. Local survival rate (affected by mortality + emigrat ion) was estimated in three distance zones using capture-recapture mod els. Survival and recapture probabilities were separately estimated fr om breeding to next breeding for F. hypoleuca and by half year trappin g periods for P. major. The local survival rate of F. hypoleuca female s showed a decreasing, although marginally significant, trend towards the polluted area. No indication of such an effect was found in P. maj or. immigrant breeders formed about 89% of the population of F. hypole uca females in our study area. Possible reasons for the low survival r are in F. hypoleuca are discussed. We suggest that the low local survi val rate of F. hypoleuca females is caused by higher emigration from t he low quality and unproductive habitat rather than by the direct mort ality of adult birds due to heavy metals. Better wintering conditions next to the human inhabitation may compensate for the possible detrime ntal effects of pollutants on the P. major population.