About one dozen sea lions are shown on docks near Pier 39 in San Francisco, Tuesday, March 2, 2010. After an abrupt disappearance that left tourists disappointed and experts baffled, sea lions are slowly returning to San Francisco's Pier 39.

The thousands of California sea lions that showed up this winter off the central Oregon coast seem to have largely moved on.

In San Francisco, last fall's abrupt disappearance of the creatures left tourists disappointed. Now they're slowly returning to San Francisco's Pier 39.

While the sea lions range widely, the mass exodus of most of a population of about 1,700 was puzzling. Some scientists suggest perhaps they simply headed north looking for food.

The Oregonian reports that schools of fish such as anchovies and sardines were ample off Oregon. One photo taken this winter off Oregon's Lost Beach between Sea Lion Caves and Heceta Head showed thousands of the animals.