Topping trees at an appropriate height, above a few live branches can be great.
Spike the tree a bunch to induce wounds.
Flush cut some branches to start cavities.
I use the tip of the bar to start hollows.
Specific cuts to specific animals. Bird and bat boxes can be installed in addition to the natural processes. An example are wood duck boxes that have an appropriate sized box/entrance hole/ height/ orientation to the water.
A wildlife biologist suggested a low power rifle to blow the tree apart.
Partial top-cuts through low branches that will droop to the ground and stay alive for a while. I've done this at my house, not on this tree.
Loose bark plates can be bat-itat.
Perch branches are good, with an opening through the branches for birds to be able to land and take off without too much impediment.
Dead Noble Fir one year after cutting. Normally I woundn't do this in the front yard, but that what the client wanted. It has a clear groundfalling dropzone for the future removal if it becomes a hazard.
I notched out triangular shaped pieces to simulate the broken effect.
In the part missing bark, there is a cavity start. Don't know if this will become used or not.
If you top the live tree, it will grow solid wood around the outside, with the heart more prone to decay, which is good, both for stability/ longevity (the tree can be girdled in a few years if you don't want the new tops to become too big).
Brush piles around the base and in the vicinity are good habitat, as well as large "coarse woody debris" like thick log sections.