Australia is well known for it’s marsupials and many of them live in trees. It can get windy, wet, and cold living in a tree so a little hollow inside a tree makes a perfect den.
Over 300 species of Australian vertebrates use tree hollows as a home for shelter, sleeping, nesting, and escaping predators!
That’s why tree hollows are so important.
Tree hollows naturally occur in older trees which are looking a bit worse for wear. The trees might even be dead!
So it’s understandable how a ‘new’ forest, full of young trees growing up within our urban towns, wouldn’t have many tree hollows.
Real estate for the arboreal marsupials is rare in new developments!
Urban areas are one of the most modified habitats in the world. Often the entire landscape is deforested so that drainage, sewers and underground power can be installed. Then the roads and the house blocks arrive as does the landscaping. New trees and shrubs are often planted as juveniles or saplings, which in 50 years will be larger established trees. In the mean time though, there are few tree hollows and the marsupials relying on them have nowhere to go.
The temporary solution may lie in nest boxes! A real home within the gum trees!
Research  is showing that nest boxes can be an effective conservation tool providing homes for arboreal marsupials around our urban developments.
The Baranduda Landcare group (Baranduda is a small town about 290 km north-east of Melbourne) has been putting up nesting boxes around their community to give the sugar glider (Petaurus breviceps), the squirrel glider (Petaurus norfolcensis) and the brush-tailed phascogale (Phascogale tapoatafa) some more places to live.
The squirrel glider and the brush-tailed phascogale are both threatened species.
Their nesting boxes are made of timber, are rectangular with a hinged lid and a round entrance hole at the front. Over 138 nesting boxes have been set up in the trees throughout 2,000 hectares of forest.
The nest boxes were surveyed to see which animals were using them, and whether the location of the nest box or its height in the tree had any effect on which animals used it.
The nest boxes were mostly used by sugar gliders and squirrel gliders.
Up to 8 sugar gliders were found squeezed into a nest box – showing that these little guys like to get cosy!
Although they didn’t see any brush-tailed phascogales three of the nest boxes had a bark nest inside them. Bark nests are made by brush-tailed phascogales suggesting that they too were using the nest boxes.
But insects liked the nest boxes as well. European honey bees (Apis mellifera – that’s the bee that makes our honey) invaded 12 nest boxes and 14 other nest boxes became homes for paper wasps (Polistes humilis). Of course these stinging insects make the nest boxes useless to sugar gliders and other small marsupials.
One of the nest boxes became a roost for Gould’s wattled bat(Chalinolobus gouldii).
So the nest boxes were occupied by marsupials, mammals and insects, but strangely no birds.
Squirrel gliders were picky about where they lived. They only chose nest boxes in flats or gullys and seemed to prefer nest boxes about 3.5 metres above the ground; they rejected the nest boxes on slopes and ridges. Trees with rough bark were the preferred choice. It makes sense as it’s easier to get a grip on rough bark. Who wants a slippy driveway?
Nest boxes were most popular during winter and autumn. In the summer the gliders may have been sleeping in the trees rather than snuggled up in a box with their friends.
If you’re interested in making some nest boxes for the arboreal animals around your neighbourhood get in contact with your local council or landcare group. They may have some additional tips for species in your area. You can also buy nest boxes from TalkingNature.com.au our online store.
 Durant et al. (2009) Nest-box use by arboreal mammals in a peri-urban landscape. Wildlife Research 36: 565-573