I've been to the BLM office for my sector so I know the area that I'm interested in is not BLM land. California land is too valuable to remain in public hands--the only land nearby that *is* BLM land is condemned for most uses because the naturally-occurring soil asbestos and mercury is so high that the ground you walk on is a hazard to your health and visitors are supposed to wash their vehicles before or on arriving at home.
For all that, they still graze cattle there.

Mostly it gets leased for mining.
Here, the ranches are fenced, but when you're talking 10,000 acres, I think it still qualifies as a ranch. Most of them are big name corporate holdings, like Harris Ranch Beef Company

, stuff like that. Some are family ranches of about 2000 acres.
So. One of the places I'd like to visit has a house about a city block's length beyond a driveway gate that is closed and locked. Should I contact those folk by leaving a note in the mailbox, or dare I pass that gate on foot and knock on the front door? The fact there's a locked gate (against cars) makes me hesitant to set foot on the driveway. And of course the pastures are marked 'no trespassing' (who can blame them? Otherwise you'd have city yahoos chasing the cattle on ATV's...) This volcano dome has lots of colored lichens and twisty trees.
Another of the places I'd like to visit is the property of a huge cattle company. Do I contact the corporate office? The draw on that land is that they have a large population of golden eagles that nest on the volcano domes there and would be great for telephoto shots.