I would be careful taking the advice some people have given. Even though you are mad about it and they are on their property. If you cannot prove that they actually cut the lanes on your property, there is not much you can do about it. You did the right thing by putting up a sign.

I would not "trash the property" or use a "fog horn." Remember, most states DNR rules state that it is illegal to impede on one's right to hunt. Any action you make that impedes on their right to hunt will land you in trouble with the game warden. I would get in touch with the land owner or them and reassure them where your property line runs.