This medium size gull is easy to distinguish because of its very bright red beak with a black stain. It is a specialist fish-eater. The most important breeding colony of Audouin's gull (up to 70% of the world's population!) can be found in the South of Catalonia, along the beaches of the Delta del Ebro.
The large concentration of one single population in this location makes the entire World's population very vulnerable to what happens to this one. Therefore, big conservation efforts are currently underway to increase the breeding colonies of this species in other areas of the Spanish Mediterranean coast: Valencia, Murcia and Andalusia. Out of its breeding period (March-May), this gull can be seen searching for fish all over the Catalan coast, but especially around the Delta del Ebro and the Delta del Llobregat.