What do you think is the more ethical and feasible approach to wildlife preservation: change human behavior to limit human impact, or create sanctuaries to preserve some of the threatened animals’ population? Why?

I think we need to do both, but I'll let you decide which you think sounds better for you personally (personally I think sanctuaries are often more effective).

Explanation:

Behavior changes It is not really ethical to continue to have a negative impact when changing our behavior can help, however, this may not be ideal as explained below

Sanctuaries It is often more feasible to create preservation sanctuaries because 1) it is hard to get everyone to change enough habits in order to create large-scale change and 2) some species require more immediate action to save, whereas changing human behavior may not be enough and/or at the right pace to preserve and expand the populations of endangered populations

Depending on the main threat to a specific population, the approach will obviously be different.