Published: Volume 57(1), June 2010. Pages 159-166.
Higher temperatures are found in the interior of woodcrete nest boxes than in wooden ones and this supposes benefits for the birds which breed in these, especially at the beginning of the breeding season. Nevertheless, this advantage could be reflected in energetic costs (thermal stress, hyperthermia) in the case of species where the breeding season is prolonged during several months, particularly in hot regions such as the Mediterranean basin. In this study we examined the existing differences between woodcrete and wooden nest boxes with regard to the microclimate of the nest and the reproductive parameters of the tree sparrow, a multi-nesting species (three clutches from April until the beginning of August). Larger clutches and chicks with a smaller body mass were found in the woodcrete nests, this latter probably due to a greater transpiration rate to counteract higher temperatures. Nevertheless, there was no difference between breeding success between box types. The results suggest that, considering a full breeding season, the virtues of woodcrete nest boxes outweigh the inconveniences and account for its great acceptance in the colony.