Long-term occupancy of nest boxes as a measure of territory quality for Pied Flycatchers

The rate of occupation of territories or nest locations has been proposed as a suitable surrogate of breeding territory/habitat quality when more precise, but costly, measures are not available. However, whether the frequency of breeding territory occupancy actually reflects its quality regardless of the habitat type is unclear. We address this issue using 22 yr of data on Pied Flycatchers (Ficedula hypoleuca) breeding in nest boxes in two contrasting habitats in central Spain: a mature, structurally complex oakwood, and a homogeneous pine plantation. Favored nest boxes in the oak forest were the earliest ones occupied, whereas the opposite was true in the pine plantation. In addition, the most frequently used nest boxes in the latter habitat were occupied by older and darker males, and also produced more offspring and recruits. These relationships were not observed in the deciduous forest. Long-term patterns of nest box occupancy may be a reliable surrogate for territory quality, but, as suggested by our results, its accuracy will depend on the heterogeneity of the habitats where nest boxes are located.Peer Reviewe