Migratory waterfowl, especially ducks and geese, have fouled up the ponds after gorging on bread thrown by passersby.

As a result, the Cupertino Parks and Recreation Department has drained Memorial Park's two ponds and has emphatically asked residents to not feed the birds.

The city estimates each bird produces about a pound of feces per day.

"The whole system clogs up," said Therese Smith, parks and recreation department director, explaining the need to drain and clean the manmade ponds twice a year.

While there is no fine for feeding the birds, Jeff Trybus, Cupertino's code enforcement officer, said there are signs in place to strongly discourage people from throwing food to them. The signs are in English, which last week left at least one woman who spoke only Mandarin unaware of what they said.

Smith said that while the free food makes the ducks and other waterfowl fat and happy, it also creates an unintended ecosystem.

"The ducks are staying in the same place and not migrating," she said.

This creates a host of other problems for the park, including damage to grass and shrubs from waterfowl grazing, messy lawns and ponds and overpopulation. The paddling of ducks and gaggle of geese in turn can lead to avian diseases, public health risks such as salmonella and hazards from birds with thespian ambitions.

"The geese have been known to get on stage during Shakespeare in the Park, forcing the actors to improvise," Smith said.

The large numbers of birds can also attract outside predators such as the night heron, which feeds on ducklings.

This could present a problem when a new batch of ducklings arrives in the spring.

In the meantime, the ponds will remain drained. And although the waterfowl have been among the few to find an affordable place to live in the city, the parks department hopes residents will give them one less reason to stay by not feeding them.