COSTS AND BENEFITS OF 2ND BROODS IN COAL TITS (PARUS-ATER)

We compared the reproductive output, local recruitment rates and survi val rates of 1 year old Coal Tit females breeding only once (''group 1 '') with the corresponding values of 1 year old females breeding twice (''group 2''). One year old females which failed first or second broo ds were excluded. Survival was estimated by the local recovery rate of females during the next breeding season. Our data do not fit with the ''cost of reproduction hypothesis'' as females with significantly hig her reproductive output and recruitment (''group 2'') did not show low er survival. We even found a significantly positive correlation betwee n production of a second brood and recovery rate the next year.