Nestbox use and reproductive parameters of Tree Sparrows Passer montanus:: Are they affected by the presence of old nests?

There is a controversy over the effects of old nest reuse oil the breeding biology of hole nesters. Some authors have Shown that the presence of old nest material could increase ectoparasite pressure and/or reduce cavity size, whereas others argue that it could facilitate nest-building and serve as an informative cue for breeding birds. However, the possible functions of old nests may not be limited to the reproductive period in burds that perform autumnal courtship or use nest cavities as shelters during the winter season, as is the case with the Tree Sparrow. The importance of the presence of old nest material on nest box choice during the non-breeding period and its implications Oil the subsequent breeding performance of this multi-brood species are assessed. Occupancy rates and reproductive parameters (such as phenology, clutch size, nestling condition, breeding Success) were compared between woodcrete and wooden nest boxes with and Without old nest material inside. During the non-breeding period no effect of box type or its content on nest box selection was discovered, but in spring it was found that the strong preference of birds for breeding in woodcrete nest boxes was independent of the presence of old nests. In relation to this latter point, evidence was found that old nest reuse Could negatively affect the reproductive Output of Tree Sparrows: Clutches were laid later, nestlings had longer wings (which presumably fledged earlier) and reproductive success was lower in nest boxes containing old nest material. The results of this study suggest that, taking the non-breeding and breeding Seasons as a whole, the accumulation of old nest material seems to be detrimental rather than advantageous to this species.