Refer to this news release by American Equine Awareness.
The advocates won’t oppose it because it can accomplish automatically what they’ve been trying to achieve manually: Getting rid of wild horses with contraceptives.
Western Horse Watchers believes there are some aspects of the machine that its developers aren’t disclosing, such as what happens if studs come in for the bait or the mares continue to feed after they’ve been darted. How will they be repelled?
On the range, will the higher horses allow the lower horses to get near it?
Western Horse Watchers Association 