The decline of Cantabrian capercaillie: How much does habitat configuration matter?

The endangered Cantabrian capercaillie (Tetrao urogallus cantabricus) has undergone a severe decline during recent decades. Capercaillies require large tracts of mature forest, and are thus sensitive to landscape-level habitat alteration. The high degree of fragmentation and anthropogenic disturbances in the habitat of Cantabrian capercaillie suggested that habitat patterns may be related to the population decline. To evaluate this we developed predictive habitat suitability models. We used a geographic information system (GIS) to integrate environmental variables and spatial context into two logistic models, comparing (a) presence vs. pseudo-absence habitat units (General model) and (b) presence vs. abandoned habitat units (Decline model). We obtained low overall habitat suitability and poor connectivity between high-suitability areas. We found evidence that habitat suitability is indirectly related to the process of population decline, and that the relationship between capercaillie presence and habitat configuration goes beyond the local spatial scale and the average size of forest fragments. We suggest that the combination of these two modelling procedures provides a deeper insight into the decline process, differentiating overall optimal and suboptimal areas (General model) and predicting the direction of eventual local extinctions (Decline model).