SAN FRANCISCO (AP) - Penguins made a love connection at a San Francisco aquarium.

In what has become an annual Valentine's Day tradition, biologists handed out red felt hearts Tuesday to African penguins at the California Academy of Sciences. The birds grabbed the hearts in their beaks and waddled around their rocky enclosure toward their nests.

Spokeswoman Kelly Mendez says it's often the male penguin who retrieves the heart and carries it back to his mate. The penguins use the felt for material in their nests, which helps reinforce the couples' bonds.

The activity is part of the academy's captive breeding program to help increase the African penguin population, which is endangered in the wild.