This is a question I come across frequently in my work as we have a fair number of documentary filmographers coming to document our work and the species we are working with. In recent years asking drones have become on the standard tools they bring, and they’re always asking about using the drones to get close to our focal species as they live on a steep cliff habitat.
Generally speaking we limit drone use to landscape shots and looking at otherwise inaccessible areas. If people were more interested in the plants I’d authorize drone use for those too, but everyone is interested in the animals.
Drones do have a place when it comes to wildlife monitoring (note I say monitoring rather than photography), but as many animals are easily disturbed by things tron the air (think large birds going after young animals and you can see why this is the case even for large animals), it’s best to keep drone use far enough away from wildlife that it doesn’t disturb it.
The distance where an animal will be disturbed varies quite a bit, but as a rule of thumb nesting birds, animals with young, and animals preyed upon by birds of prey should all be avoided.
Here are some resources, both academic and non-academic from conservation organizations, birding organizations, and photography organizations: