It's not easy finding food at sea. Seabirds often stay aloft, scanning the churning waters for elusive prey. Most seabirds take fish, squid, or other prey from the first few meters of seawater. Scavenging is common.

But there are other tactics. Frigatebirds, skuas, and gulls rely on the success of other seabirds. These large, strong birds chase, harry, and attack their targets until they regurgitate or drop the prey they've just caught. They're the pirates of the seabird world, stealing hard-earned meals from other species. This behavior is known as kleptoparasitism, from the Ancient Greek word kléptēs, thief.

The strategy is brutal, effective, and a core behavior for these important seabirds. But as our new research published in Conservation Letters shows, it comes with major risks for the thieves. The new strain of avian flu is killing birds by the millions—and we found kleptoparasitism could spread the virus very easily.

Food thieves at sea

It's not that frigatebirds, skuas, and gulls can't hunt. They can and do catch their own food. But hunting fish and squid is hard work. It's much easier to use extortion tactics to win the food from other seabirds.

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