Botanical name        Eucalyptus propinqua X biturbinata

A common name        Small fruited Grey Gum

Need to wait a while to be fairly sure.
Young plant
As above
Reasonably mature
Eucalyptus propinqua X biturbinata
The Grey Gums are the 3 thin trunks to the right.
Grey Gum is a popular Koala food tree.  It is interesting to see where our Grey Gums have claw marks (though they are not necessarily Koala claws).  Over a fair length of the 1.2 km length on the Northern edge are Tallowwood, many very large, often with canopy touching, or nearly so.  Tallowwood is another very popular Koala food tree.  On one high flat ridge, actually a spur off the adjoining property to the North, we have Grey Gum.  On the North end of this ridge most if not all Grey Gum are well claw marked.  On the Southern end of the ridge there is another colony of Grey Gum, mostly unmarked.

I know other people in the area have heard and in some instances seen Koalas. My best bet is to go looking for Koala scats.
Eucalyptus propinqua X biturbinata bark
Eucalyptus propinqua X biturbinata bark
These are two photos of the same section of trunk, the top photo is zoomed in a litte more but is a little lower down.  You can orient yourself with the protractor shaped dark scratch which has a set of 3 deep orange scratches across it.  This large leaning Grey Gum was immediatley to my left when I was taking the photo of the Juvenile specimens shown above.  We also have at least one Lace Monitor resident as well, some of the larger scratches could easily belong to them.