Every person who, within any public cemetery or burying ground, kills, wounds, or traps any bird, or destroys any bird's nest other than swallows' nests, or removes any eggs or young birds from any nest, is guilty of a misdemeanor.
This law has a decent baseline of strangeness from the oddly specific scenario of trapping birds or interfering with their nests in public cemeteries. But the exclusion of swallows' nests from the law's reach takes section 598 to the next level. Perhaps singling out swallows has something to do with their airspeed velocity, or maybe there is a different reason for this distinction entirely, but I am inclined to believe that this particular law regarding birds is not governed by reason.
A former classmate informed me that the law appears to single out swallows due to their unique nesting habits. Swallows tend to build mud nests in clusters, and their nests can be unsightly and damaging to property. This appears to be the basis for Penal Code section 598 singling out this particular bird.
Be warned, however, that while the destruction of swallows "nests" are not prohibited under section 598, the removal of eggs or young birds is not limited. This article from the OC Register also highlights that damaging or removing an active swallows' nest may violate the Migratory Bird Treaty Act of 1918 and that those seeking to remove nests between February 15 and September 1 can only do so with a permit from the U.S. Fish and Wildlife Service.