(SOUNDBITE OF IMITATION SEAGULL SCREECH)
AUDIE CORNISH, HOST:
That is not a seagull. That is a human imitating one, and we'll explain why in a moment.
AILSA CHANG, HOST:
A lot of people in coastal Belgium hate seagulls. That's because in the last few decades...
JAN SEYS: Seagulls started breeding on the roofs.
CORNISH: Jan Seys is with the Flanders Marine Institute in Ostend, Belgium. He points out that his country has about 37 miles of coastline, a narrow slice between France and the Netherlands.