A few of the bluebird nestboxes at Tanglewood Park have
been modified with a 3" plastic tube at the box entry or with a 6" PVC pipe covering
the mounting post (or both). The plastic tube at the entry is intended to reduce
predation by preventing a predator such as a raccoon or feral cat from bending its
foreleg when reaching into the interior of the box, thus preventing the animal from
"raking out" the contents. The PVC pipe covering the mounting post is by its nature
slippery, and due to its diameter, difficult to grasp by climbing animals such as
raccoons, cats and squirrels thus discouraging a climb to the nextbox entry.