As for wildlife - http://www.nrcresearchpress.com/journal/juvs - I saw a presentation by Dr. David Bird on the use of small drones / UAS for wildlife research and he said that his team had found them to be drastically less disruptive than other methods of research, and that animals became acclimatized to their presence very quickly. Obviously, that doesn't really answer the question as to wether there will be long term effects, but it seems that most animals get used to them/don't mind.
From the NPS website, "Launching, landing, or operating an unmanned aircraft from or on lands and waters administered by the National Park Service within the boundaries of [insert name of park] is prohibited except as approved in writing by the superintendent."
Because the FAA controls jurisdiction over the airspace, the NPS can't prevent UAV flights, but, they can regulate the operators.
Source: Interdrone conference presentation by Marke Gibson that I attended 2 weeks ago.
"in the airspace above" is a separate distinction, and one they do not have control over.
So I guess the problem has ways of solving itself.