Category 
Description of variables 
Abbreviation 
Unit 

Anthropogenic environmental variables 
Distance to the nearest city 
City 
km 
Distance to the nearest metropolis 
Metro 
km 
Distance to the nearest road 
Road 
km 
Distance to the nearest highway 
Highway 
km 
Distance to the nearest railway 
Railway 
km 
Human population density in 2005 
Hpopden 
p/km^{2} 
Poultry density in 2005 
Poultryden 
p/km^{2} 

Physical environmental
variables 
Distance to the nearest lake or wetland 
GLWD 
km 
Distance to the nearest Ramsar site 
Ramsar 
km 
Digital elevation model 
DEM 
m 
Slope aspect 
Aspect 
° 
Slope gradient 
Slope 
° 
Mean annual potential evapotranspiration 
Mapet 
mm/km^{2}/year 
Mean annual aridity index 
Maaridity 
No unit 
Mean monthly precipitation 
PrecJan to Dec 
mm 
Mean monthly minimum temperature 
TminJan toDec 
°Cæ*10 
Mean monthly maximum temperature 
TmaxJan to Dec 
°Cæ*10 
Monthly NDVI 
NDVIJan to Dec 
No unit 

Interaction variables 
Poultry density * distance to the lake or
wetland 
PoultrydenW 
No unit 
Poultry density * distance to the Ramsar
site 
PoultrydenR 
No unit 