2 things - as above, if a climbable structure is too close to a barrier or a wall, the animal can clip through via the huge hitboxes and escape (or get stuck in a wall which happened to me several times). Also, if an animal goes to high above the barrier height, even if they're in the center of the exhibit, they'll get crated and returned to the gate as ... not escaped exactly but I think they get classed as impacted by some terrain conflict - when that happens the animal is moved back to the gate. If you are using null barrier you can just drag it up really high and it should reduce the boxing issue.