Avian breeding densities are often considered to be suitable proxies of habitat quality. However, this simple method to estimation of habitat quality has some shortcomings. Better than simply relying on breeding densities it is to consider also survival and reproductive success of birds inhabiting respective habitats. Here we compared the proportion of occupied nest-boxes and reproductive success of birds between two contrasting environments – deciduous (Quercus petraea) and coniferous (Picea abies) forests. Proportion of occupied nest-boxes was larger in the oak forest. Here also the two most frequent breeders, the great tit (Parus major) and the collared flycatcher (Ficedula albicollis), started to breed earlier in the season. The great tit had also larger clutches and breeding success in the oak forest. However, they laid second clutches more frequently in the spruce forest. This study offers only weak conclusions about quality of the two habitats. Further studies would benefit from space replicates and long-term monitoring of both adult and offspring survival.