they aren't hogs that have just been "turned out" they are wild, russian boars, yes some have crossed with the occasional domestic hog that's gotten loose...But they have a totally different look than a domestic hog. Long snoot, big tusks, and the males have a shoulder plate...kinda like armor under the hide.
They can root up a hay field over night, make it look like someone's taken a root plow in and turned the ground.
They are good to eat (sows) but the boars have a hidious smell, that just won't go away. We have them here too, have trapped em in traps like that, snared em with lil wire snares attached to fence posts, shined em at night and come home with 4 or 5 at a time to dress out. But you can see them any time of the day. I dont know the proper word for a group of hogs...lol but we've seen "herds" of em with as many as 40 to 50 at a time. Oh and have seen boars weigh as much as 600 lbs