Voters will decide in November whether to ban small hen cages in the state's egg industry as of 2015.
The ballot measure got more than the required 433,971 signatures from registered voters, the California Secretary of State's Office announced late Wednesday.
The measure, sponsored by the Humane Society of the United States and allied groups, would require that cages provide enough room for hens to stand up, lie down, turn around and fully extend their limbs.
They say this is not possible with industry practice that allows as little as 67 square inches of cage floor space per hen -- less than a sheet of letter paper.
"Californians will have a choice this November as to whether they want to enact a very modest anti-cruelty measure that would improve the lives of millions of animals in California," said Paul Shapiro, director of the Humane Society's factory farming campaign.
Opponents, including leaders in the Northern San Joaquin Valley's large egg industry, say the cages protect the birds from disease and injury.
They also say consumers can buy cage-free eggs, but the measure would increase prices for everyone.
"It would be tremendously expensive and, in fact, drive the egg industry out of the state," said Scott Macdonald, spokesman for Californians for Sound Farm Animal Agriculture, an industry group that opposes the initiative.
The measure would not affect chickens raised for meat, an even bigger industry in the north valley. Most of these birds are allowed to roam in large barns.
The 2015 deadline is intended to give egg producers time to revamp their operations if the measure passes. Already, the American Egg Board has contributed $400,000 toward research on the issue at the University of California at Davis.
Joy Mench, an animal science professor at Davis, agreed that cage-free hens can be prone to disease and injury, and produce pricier eggs.
She said a promising alternative is cages that are large enough to provide room for nesting, roosting and other natural behavior. They are beginning to be used in the European Union, where small cages will be banned as of 2012.
The California measure also would ban small enclosures for cattle raised for veal and for pregnant pigs. These are not major industries in the north valley.
Bee staff writer John Holland can be reached at firstname.lastname@example.org or 578-2385.