The migrants, smugglers, coyotes etc are far less likely to bother you if you are armed. Our family friend sees them crossing his property all the time and messing with his infrastructure (cutting fences, messing with out buildings, stealing etc), but they very typically avoid him. The saddest part is when he finds a body, or whats left of one. This isn't him, but its an example of what is going on.

You also have feral hogs, coyotes, bobcats, mountain lions, black bears, Russian boars that get to over 500lbs are aren't shy etc. These ranches are pretty large and remote, so you are on your own out there. Our friend's ranch is several sections, so its huge, but small compared to a lot of them in the area. I have neighbors on much smaller acreage that have rifles in their trucks by default, but that's strictly for varmints.