They are in Wisconsin too, though the agency is a little loopy at times. As I noted in my last couple posts, I'm suspicious of the characterization of the non-disclosed "directive".
Game wardens do have authority to go on private land to enforce the game and fish laws. They only have authority to enforce game and fish laws, so this is why they have a bit more leeway than other officers. They have full authority to enforce all the laws in State Parks. I recall an older warden saying that during prohibition, if a game warden found a car with a load of bootleg liquor, he always ignored it because it was none of his business.
However, wardens, I believe, are not allowed to trespass on private land unless they have a reason to enforce the game and fish laws there. This has always been a “grey area” in warden activity. The “training” that I got (wink, wink) was that a “good warden” could always find a reason to go onto private land, even if one was not obvious.
One warden instructor said that even though a warrant was legally required to search an automobile without permission, once he got out his pry bar and indicated that he would force open the trunk, he never failed to get permission to do so! Another warden told of how he thought it was a good idea to sneak into a person's boat house and search for illegal fish, because he was sure the guy was a violator, even though he did not have enough evidence for a warrant.
Judges often defer to the local game warden in matters of the game and fish laws. The was even one fellow who was convicted of an offense that did not exist, because the judge simply relied on the warden, who made a mistake in the law!
A few years ago, a zoning official went onto private property in Wisconsin, without permission, to determine if there were a zoning violation, and the zoning official was charged with trespassing, and convicted of it, so I am not so certain that a totally free hand for wardens to go on private property is absolutely legal.
If a warden is on private land investigating hunting or fishing, and has ascertained that the hunting or fishing that he is investigating is legal, I believe that it is then legal for the landowner to order him off of the property. I do not know of any test case of this, however.
Being a conservation warden in Wisconsin does not give a warden a blank check to trespass on private property at any time.
I treat all law enforcement with respect, because it is smart to do so, but my experience in the warden force in Wisconsin helped me to realize that it is foolish to put yourself at legal risk by trusting that peace officers always have your best interests in mind. Often they do not. Often they are in a bad mood, or need to impress the boss, or have an agenda of their own. You never know, so it is wise to be careful as well as respectful, and to realize that every encounter with a peach officer has an element of legal risk.