I felled a bunch of Siberian Elms last fall, well ahead of deer season. In one spot, the easy felling direction of the trees created a nice u-shaped structure.
When I went back a few weeks later to put up game cameras, it was obvious the deer had really loved the chainsaw work. They ate a bunch of the green new-growth off of the "tops" of the felled trees. They set up a scrape and a licking twig. The entirety of the inside of the "U" was either bedded down grass or hoofprints. When I walked inside of the structure, it was very easy to see out, but would have been difficult to see any still animal from the outside.
The deer that have survived a few thousand years of culling by bow and arrow, and then by firearm are pretty darn smart these days.
