The supreme court has an "open field" doctrine which put simply says you have no reasonable expectation of privacy in an open field, hence they can investigate on your land without a warrant. You only have a reasonable expectation of privacy in your person, papers, home, business, and vehicle.
To put this into real life context say you have a farm, you have a reasonable expectation of privacy in the home, barn, garage or any outbuildings, and in the yard around your home, but not in your fields or woods.
As far as the trespassing I haven't researched that yet, but will get back to you when I do.
The bigger question for me is these DNR policies taken out of the 2009 Hunters Regulations:
It is illegal to:
• possess any firearm from 12:00 midnight–11:59 p.m. on November 20, 2009 unless
the firearm is unloaded and enclosed within a carrying case. Exceptions: target
shooting at established target ranges, target shooting on private lands by landowners
and immediate family members who live with them, waterfowl hunting during
open season, hunting game birds on licensed bird hunting preserves, and hunting
small game in CWD Management Zone units.
Note: An established target range means an existing location that is set up for
target shooting with firearms as its major purpose.
• It is illegal to possess any rimfire rifle larger than .22 caliber or any center-fire rifle
.22 caliber or larger during any gun deer season in shotgun only areas unless it is
unloaded and enclosed within a carrying case.
Notice they don't say "its illegal to hunt with", they say its illegal to POSSESS! So the U.S. and Wisconsin Constitutions, as well as Supreme Court case law is all suspended from 12:00 midnight–11:59 p.m. on , 2009??????
So no OC'ing on November 20th anywhere in the state, and no toting a rifle around unless it's a .22 or smaller in shotgun only areas. If you don't know what shotgun only areas are your fuc*ed I guess.