Therefore it is extremely important that the trap be strategically baited to insure that most if not all of the pigs in a sounder have entered the trap.
Guillotine trap door trigger.
I personally prefer the guillotine door as it generally has a bigger opening and it is positively closed with an active latch to prevent pigs from rooting.
Rooter lifting gates require that a hog use its nose.
Photo courtesy of texas agrilife extension.
One drawback of guillotine gates is that they do not allow additional pigs to enter once the trap has been triggered.
Guillotine or drop style doors are called single catch doors because once the trap has sprung that is the door has closed no more animals can enter the trap until it is manually reset.
Guillotine or sliding drop gates use a trip wire to trigger the door to fall.