FGC §2016: (a) It is unlawful to enter land for the purpose of discharging a firearm or taking or destroying a mammal or bird, including waterfowl, on that land, without having first obtained written permission

(a) It is unlawful to enter land for the purpose of discharging a firearm or taking or destroying a mammal or bird, including waterfowl, on that land, without having first obtained written permission from the owner, the owner’s agent, or the person in lawful possession of that land, if either of the following is true: (1) The land belongs to, or is occupied by, another person and is either under cultivation or enclosed by a fence. (2) There are signs of any size and wording forbidding trespass or hunting or both displayed along all exterior boundaries of the land, at intervals not less than three to the mile, and at all roads and trails entering the land, including land temporarily inundated by non-navigable waters flowing outside the established banks of a river, stream, slough, or other waterway, which fairly advise a person about to enter the land that the use of the land is so restricted. (b) Nothing in this section restricts the right of the public to use navigable waters for hunting, fishing, or other public purpose as guaranteed under Section IV of Article X of the California Constitution.