Slender-billed Gull ~ 1st. S ~ Ebro Delta, SpainSlender-billed Gull ~ 1st. S ~ Ebro Delta, SpainSlender-billed Gull ~ 1st. S ~ Ebro Delta, SpainSlender-billed Gull ~ 1st. S ~ Ebro Delta, SpainSlender-billed Gull ~ 1st. S ~ Ebro Delta, SpainSlender-billed Gull ~ 1st. S ~ Ebro Delta, Spain