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Table 1 Predictor variables used to model the occupancy and the productivity of European Rollers in artificial nest boxes in Lazio region, Central Italy

From: Nest box selection and reproduction of European Rollers in Central Italy: a 7-year study

Habitat variables Definitions
Nest position
Distance from arable fields (including cereals) Euclidean distances between the nest box and the nearest patch of the given habitat type
Distance from urban areas  
Distance from orchards (including olive groves and wineyards)  
Distance from scrublands  
Distance from fallow fields  
Distance from forests  
Distance from grasslands  
Terrain
Altitude Meters above sea level
Solar radiation Amount of solar radiation, expressed in Wh/m2
Habitat composition
% of arable fields Percentage of each habitat variable in a circular buffer of 600 m of radius around the nest box
% of scrublands  
% of fallow fields  
% of urban areas  
% of orchards  
% of forests  
% of grasslands  
Habitat structure (landscape metrics)
Shannon diversity Measure of relative patch diversity in the 600 m buffer
Number of patches (NumP) Total number of patches in the 600 m buffer
Mean patch size (MPS) Average patch size in the 600 m buffer
Mean perimeter/area ratio (MPAR) Shape complexity in the 600 m buffer
Edges density (ED) Amount of edge relative to the landscape area in the 600 m buffer