Brushtail Possums will use nest boxes with entrance diameters from 100mm and larger (90mm for small brushies). To consider, is that larger (130-150mm) entrances will let more hot air out, and cold air in during winter months, and also risk predation by large owls and harassment by the many daytime creatures that they prey on at night. This nest box design is for the mid-range entrance that a Brushtail Possum will use.
Here is a diagram with key design features for all nest boxes. Wildlife carers recomend adding a horizontal branch to below the nest box entrance for the Brushtail Possum nest boxes. This is completely optional, however please do ensure that there are parallel groves cut into the nest box – inside and outside, so that if (when) a large parrot chews the branch off the nest box, there is still grippy access for all possible nest box users – inside and outside.
Here is some information on the different materials to use, or not to use when making your nest box.
