The real risk, stated plainly
Coyotes are present across nearly all of California, including dense urban-adjacent open space, and mountain lions inhabit much of the same hill and canyon habitat where grazing projects often work. Any herd left genuinely unprotected on open ground overnight is at real risk — this isn't a theoretical concern professional operators wave away, and it's a central reason grazing companies invest heavily in the measures below rather than just fencing and walking away.
Layered defenses, not one silver bullet
Livestock guardian dogs living with the herd are the primary defense — their scent, presence, and bark deter the large majority of predator approaches before they escalate. Electric netting adds a physical and psychological barrier of its own. Herd bedding areas are typically chosen and sometimes reinforced with portable panels for the highest-risk overnight hours, and some operations use additional deterrents like motion-activated lights in known high-pressure areas.
None of these measures is individually foolproof, which is exactly why professional operations layer them rather than relying on any single one — a guardian dog backs up the fence, the fence backs up sensible bedding-site choice, and daily herder visits catch problems before they compound. Losses still happen occasionally in this industry, as they do in any outdoor livestock operation, but a serious operator treats predator management as a standing cost of doing business, not an afterthought.