In one of his books, Charles Alsheimer tells a story about a three and a half year-old buck that had a radio collar on it, and how he had been asked by a New York State Dept. of Environmental Conservation deer biologist to help look for it, after the season had closed. There were six men total, all of them experienced (and successful) deer hunters. They surrounded a plot that was somewhere in the neighborhood of a couple of acres, where the radio collar's receiver had indicated that the buck was hiding. They lined up a road, and drove towards the road . . . and none of them saw the buck cross the road. From what the recever was saying, the buck had easily outwitted them and had gone right between two of them.

Now, you may be asking, That's fine, Muddy, but just what the deuce are you driving at? My point, in a long-written way, is that deer can evade humans in a very small enclosure. Continuously.

Having written all that, I'd say that 1000 acres would be the absolute minimum.