Code from: When and where do waterbirds need water? Inferring candidate restoration areas from spatio-temporal variation in surface water availability

Aim  Globally, about 850 bird species depend on surface water
habitats either year-round or during migration. However, large-scale
analyses examining how different groups of waterbirds are associated with
surface water across various regions and during different seasons are
lacking. This study analyses this relationship using high-resolution
satellite imagery to determine when and where surface water and associated
resources might be improved.   Location Western Palearctic
(Europe, Middle East, Northern Africa)   Methods We correlated
monthly counts of 40 waterbird species with surface water availability in
the Western Palearctic at a 100 x 100 km grid cell resolution. We then
identified where and when surface water might be limiting for waterbird
numbers, using waterbird count data and the most recent release of
high-resolution satellite imagery from the Copernicus project.  
Results  Surface water availability was higher in the
East-Atlantic flyway than in the Black Sea – Mediterranean flyway, but
differences were small, while bird abundances (after correction for
observation effort) were comparable. The relationship between surface
water and waterbird abundances was typically positive and slightly
stronger in the East-Atlantic flyway. However, it was negative during
summer in the northern regions, where many waterbirds breed. Correlations
were stronger for ducks and other strictly wetland-dependent birds,
reflecting their more exclusively aquatic feeding behaviour. Crowdedness,
calculated as the number of birds per surface water area, was higher in
autumn compared to spring migration.   Main conclusions Our
results confirm that the importance of surface water availability for
waterbirds varies seasonally and geographically. In addition, our maps
integrating bird counts and surface water help to strategically prioritise
regions where water availability could be limiting and high crowdedness
implies a vulnerability for waterbirds, e.g. in terms of resource
competition or disease transmission. These include parts of the Iberian
Peninsula, the UK, northern-central Europe, the Levant and Northern
Africa.