As best I can tell, the Disney U is mainly populated by a mixture of regular humans and what the fanbase refer to as 'Dogfaces', i.e, people with the little black dog-noses and (usually) dog ears like the Beagle Boys. In most places, judging by the comics, Dogfaces are the major ethnic majority, but in others, regular people appear to dominate, which is where the movies are set. Anthropomorphic characters such as the Ducks are a distinct presence, but seem to be a relative minority. The three groups are not segregated - one does see regular humans alongside Dogfaces, and Dogfaces alongside regular humans - and one would imagine that they crossbreed amongst each other with a relative lack of discrimination, which would explain the stories where, say, Daisy Duck is being courted by a Dogface. (It would also explain the odd-looking characters that pop up every now and then which appear to be neither fish nor fowl, such as the largely humanoid guy with a head like Mickey Mouse's seen in one story, or the mad duck professor with dog ears seen in another, or Mickey's nemeses Drs. Ecks, Doublex, and Triplex, who resemble nothing so much as a cross between Dogfaces and apes. Obviously, they are the result of biracial coupling.) The Rescue Rangers would appear to be set in one of the areas dominated by regular humans (looks like New York to me).