When faced with a question like this, I like to remember a story by the late Gene Hill titled "When No One is Looking" from his book Sunlight and Shadows. In it one of his hunting mentors, Judge Landis, tells the following tale:
"'I think a lot about hunting; it's a complicated piece of business,' he said. 'But I remember one thing that came to me when I was a little older than you are, I was out by myself, with one of my father's good bird dogs--and one of his good guns. He didn't mind; he believed that things are meant to be used. And while I was out, I had what I like to think of as a T-H-O-U-G-H-T.' (He spelled it out and it sounded like it was all in capital letters.) 'I haven't had all that many, so they're not all that hard to remember. I was hunting grouse, and a young bird flew up in front of the dog and landed on the branch of some kind of pine...tamarack, maybe. I had already missed three or four and hated to come home empty-handed; my father always had something to say about that. I swung the gun up on the bird, and then I put it down. That's when I had my THOUGHT: I thought that here I was alone, doing the right thing--a thing I knew that many men wouldn't blink an eye over--and that I was in the most vulnerable of moments--when no one is looking. I knew then that I'd turn out all right. I knew then that I was an honest person. That I could trust myself. What do you think of that?'"
When no one is looking, do the right thing: always obtain permission before attempting to retrieve game on private land.
Good luck, and good shooting!