With their caustic droppings all over the city, pigeons both cause health concerns and etch the surfaces of historically important buildings. But poisoning our feathered friends is sooo not the answer.

Now, a California company has come up with a more palatable solution: pigeon birth control.

Innolytics L.L.C. has received permission from the Environmental Protection Agency to use an oral contraception that causes the birds' eggs to fail.

Called OvoControl P, it contains nicarbazin, used to prevent disease in broiler chickens. The side effect is a weakening of the yolk membrane.

It is considered safe for the pigeons and harmless to any predator, like a falcon, that might nab one for dinner.

"Our technology bridges that gap between animal-rights and wildlife-management groups," says CEO Erick Wolf.

The drug is in food that is dispensed from a box on a roof. When a timer goes off, the device spews the food like salt from a highway truck.

Most of the time, pigeons perch on ledges and look down, scouting for the odd bits of soft pretzel and the like that humans unwittingly offer up. But Wolf says the birds are trainable. Go to the roof at 8:30 every morning and toss food. Pretty soon, look out at 8:20, and they will have gathered.

The company got its start with birth control for Canada geese, the scourge of many a park. In the wings, so to speak, are formulations for Muscovy ducks, nonnative hybrids and mallards.

- Sandy Bauers