Mainly by their preferences. They can be quite stubborn with their likes and dislikes. And the distance they travel to stay in a preferred spot. The one on the burn pile, for instance...I had put her on the rose bush. I had relocated her to the rose bush from another location, as the dh was weed trimming that day. Well, she didn't like the rosebush, but the burn pile was in clear view of the rb, Although about 100' away.
I relocated her from the burn pile.....because it will be set alight eventually. I put her behind the shed building. NOT in plain sight of the burn pile.
Yesterday.....I found her in the exact same spot. Burn pile.