Flying away from people and traffic, quadcopters seem much noisier!
There are many slow-fly planes and gliders you might consider for nature photography. You can't loiter the same way you can with a quadcopter, but you can shut the motor off for brief periods and glide which will disturb wildlife less than four screaming motors.
You can also generally count on longer flights covering more distance with a fixed wing craft, so installing longer range radio gear pays off.
You may even get close to things too far away from a road to get at with a quad, but wherever you fly, you might crash, so better be prepared to do the "walk of shame" or write off your craft.