Okay, so here after my dilligent search I have found the following information on having chickens in OC CA:
http://www.animallaw.info/statutes/stuscaodgilroy_orangecounty.htm#orangecounty
Sec. 4.20. Swine, bees, chickens, roosters, peafowl, ostriches and other "Ratitae," and livestock prohibited except in agricultural zones.
(a) It is unlawful for any person to keep, maintain or permit to be maintained bees, swine, llamas, roosters, chickens, pigeons, turkeys, pea fowl, water fowl, ostriches and other "Ratitae," or livestock on any premises within the city that have not been zoned for agricultural use. The term "swine" as used herein does not include pot-bellied pigs harbored in strict accordance with restrictions related to noise or sanitation as provided in this chapter.
(b) It is unlawful for any person to construct, establish, conduct or maintain or cause to be constructed, established or maintained, or engage in, except as otherwise provided for in this chapter, any dairy, stock yard or stock corral, cattle ranch, rabbit or poultry ranch, or public stable, on any premises not zoned for agricultural use. Where such uses are existing on the effective date of this ordinance, then such use shall be allowed to continue as a nonconforming use.
(Ord. No. 95-9, §§ 2, 3, 5-1-95; Ord. No. 98-1, § II, 1-5-98)
That being read, I cannot have chickens (legally) in Fountain Valley.