Demographic responses of Middle Spotted Woodpeckers (Dendrocopos medius) to habitat fragmentation

We examined the demographic response of Middle Spotted Woodpeckers (Dendrocopos medius) to habitat fragmentation in an 880-km(2) study area in the Cantabrian Mountains (northwest Spain), 2000-2005. We used a set of reproductive parameters to examine 26-72 nests in 10-14 habitat patches. Fifty-nine of 72 nests (81.9%) were successful (i.e., at least one fledgling was produced). Average clutch size was 5.1. Seventy of 94 hatchlings (74.4%) survived to fledging. Mean number of fledglings for successful nests was 3.1, average fledgling mass was 50.6 g, and mean fledging date was 21 June. Generalized linear mixed models showed no significant correlations between patch sizes and any of the reproductive parameters, which suggests that habitat fragmentation did not increase nest predation and parasitism pressures or reduce food in small habitat patches during the breeding season. In 33 habitat patches inspected (4.2 years on average), 190 of 228 territorial males (83.8%) were paired. Pairing success varied strongly across years (77.1-97.4%) and was lower in smaller and more isolated patches. Low pairing success in isolated patches may be associated with disruption in connectivity between habitat patches. On the other hand, the presence of unpaired males in small patches with low numbers of territories suggests that females may use the abundance of conspecifics as an indicator of habitat quality when deciding to mate.