I had an incident with my BP feeding on aspen, but I think it's a pretty rare thing. When he struck at the mouse, he got an aspen chip lodged sideways in his mouth, and couldn't get it loose. We let him work at it for a couple minutes, but it seemed to be really freaking him out, so I held his head, and hubby pulled it out. We left him and the mouse alone, and he eventually came back and ate it, but it was a little scary.

Now I'm feeding him F/T rats, and he doesn't even bother striking or constricting them , so I don't worry about the aspen as much. I like a layer of aspen over the newspaper, because the ink worries me a little. If I can find a good, cheap supply of blank newsprint or butcher paper, I might just dispense with the aspen altogether.