If there is one thing San Francisco Giants fans know better than playoff success, it may be gulls.

The birds have an uncanny way of showing up at AT&T Park during the eighth or ninth inning of every ballgame. And as soon as the crowd thins out, they're in the stands fighting over garlic fries and leftover hotdog buns.

But how do the gulls know to come in the first place? Scientists have a few theories. Listen below.

Some think the birds recognize the sounds of "Take Me Out To The Ballgame" played during the seventh inning stretch. Others think the birds know to arrive when they see people starting to head to the parking lot. Or maybe they know to stop by the stadium if the lights are on? Read more theories.