If you're stuck in a pond in the San Francisco Zoo, it's not easy to swim to South America. That, however, is what a flock of 52 penguins appears to have been trying to do since Christmas Eve, and zookeepers admit they have no idea how to get them to stop.
The trouble started when six penguins from Sea World in Aurora, Ohio, were shipped out to join the San Francisco group. The West Coasters had filled their days with an easy routine: eating, preening and paddling in their 130-ft. by 40-ft. pool. From November to February, they had retreated to their burrows. But not this year.
Shortly after the Ohio penguins arrived, they jumped in the pond and began swimming rapidly in circles. Soon the others joined them. They have kept at it since, stopping only at dusk, when they stagger out to sleep. "We've lost complete control," says Jane Tollini, the penguins' keeper.
All the birds are Magellanic penguins, which weigh about 7 lbs., stand about 18 in. and reach a top swimming speed of 15 m.p.h. In the wild, they would make migrations of 2,000 miles along the coast of South America. That equals 26,400 laps around the zoo's pool, and the birds appear to be trying to swim every one of them.
Why the penguins have come so unhinged is not clear, but simulated migration is only one answer. Penguins are exceedingly social and suggestible; a flock at a New Orleans aquarium once went into a similar swimming frenzy when they were moved to a temporary pond. It's possible that the trip to San Francisco triggered similar behavior in the Ohio birds and that the longtime residents just followed.
The penguins have been sleeping less and skipping some meals but don't seem to have been harmed by all the exercise. In April, when the penguins are due to lay eggs, zookeepers will see if they have been skipping something else too. --By Jeffrey Kluger