Four more boxes were installed at the same site several years later, this time with the entrance at the rear of the box and only 65mm dia. Both changes were intended to deter other animals from competing with the gliders. When checked 8 months later all boxes were being, or had been, used by gliders, with no sign of interference by other animals.  After a couple of years, however, rainbow lorikeets nested in one of them.

A smaller entrance of around 50mm or less was suggested by the work of Barry Traill and Alan Lill, from Monash University, who found that, to exclude squirrel gliders from a nestbox, they had to half-block a 50mm diameter entrance (thus forming a semi-circle).  [Reference:  Traill, B.J. and Lill, A. (1997) "Use of tree hollows by two sympatric gliding possums, the squirrel glider, Petaurus norfolcensis and the sugar glider, P. breviceps", Australian Mammalogy, 20, 79-88].