Ok so I have just installed some log rolling around my outdoor guinea pig pen. It is around 44cm high, that's about a foot and a half. So I went out earlier to find one had gotten out. I put him back in to see whether he would try again. He looked up at the height, decided he might make it, then leaped on top, then over! Is this normal behaviour, I didn't think guinea pigs liked heights! Now I have to find some other form of barrier, aargh!