Yes, I'd capture some black snakes and take to our remote round top. They do very well.
Poisoned rodents in the open may be captured by owls or hawks.. leading to their death also. I know of a couple owls went that way.
There are poisons out there that are not dangerous for secondary kills. One has to do their research though to find the right one if they are going to be used in the open. Good point.
