Fig. 4
RLQ and fourth-corner analyses showing a standardized eigenvectors relating species ecological traits (grey bars) and island characteristic variables (black bars) along RLQ axis 1 (describing occupancy frequency), and b the bivariate relationships between island attributes and species ecological traits for winter residents (WR), winter visitors (WV), summer residents (SR) and summer visitors (SV). A area, HR habitat richness, BI buffer isolation, DI distance to mainland, BM body mass, MC movement capacity, VS vertical specificity, HS habitat specificity. Negative scores along the axis 1 in section are present positive associations between occupancy frequency and ecological traits as well as island characteristic variables. Blue cells in section b represent significant (p < 0.05) negative associations and gray cells were non-significant