This is a brilliant design by Hollow Log Homes for Kookaburras. Within two weeks of installing my Kooka nest box, purchased from Hollow Log homes, my occasional visiting Kookaburra pair had laid their first egg! Now three years later, there have been three families raised in the nest box.
Here is a diagram with nest box key design features. Just note that the climbing groves are not necessary for this Kookaburra design, as the nest box is very shallow.
Here is some info on the different materials to use, or not to use when making your nest box.
