I always just thought, when I thought of it, that pants wouldn't work on those squat little bodies. I mean, there's a Don Rosa comic where one of the nephews is talking about how they need some shoes for something or other, and one of the others says "For THESE feet? Forget it!" It's pretty much the same principle - they don't wear pants because the shape of their bodies - oval lower abdomens, thin skinny legs - would make keeping them on a bit of a chore. Anyway, they don't NEED pants - they're covered with soft, insulating feathers, and their private parts are about as visible as a regular duck's would be. All the guys who wear pants - Goofy, Gyro Gearloose, the Beagle Boys, most of the regular people - have more human bodyshapes, so it makes sense for them. (Incidentally, Horace Horsecollar does NOT wear pants; he's the lone exception among the latter group - but he's kind of a weird guy, anyway. And Mickey Mouse does wear them despite having a bodyshape very similar to the ducks, but I'll ignore this because A: it has varied quite a bit over the years; sometimes he's got a very humanoid body, while in others he's got the original-shaped bod, and B: I hate Mickey Mouse, so if he's the odd man out, that's fine with me. ) As for their anthropomorphic status, Carl Barks was asked about this a fair amount, and he said that he always wrote the ducks as if they were regular human beings who just happened to look like ducks. It explains a lot - for example, nobody seems to have any problems with eating chicken or turkey, or eating fried eggs, despite the fact that this ought to be tantamount to cannibalism. Also, there are plenty of regular-sized non-anthropomorphic birds who interact with the ducks like regular birds would with humans. So one may safely assume that Goofy and Horace and all the other anthropomorphic animals are simply humans who live in a world where such wildly unconventional bodytypes are common - they may LOOK like dogs, horses, ducks, mice, whatever, but they're really just humans. Pluto is, of course, an exception to this - he's just a regular dog - and as for the chipmunks, I'm pretty certain that Chip and Dale are real chipmunks, given their relative size as compared to the others and the fact that they generally live in tree trunks. But there's a tiny animal subculture in place in the Disney universe - the mice from 'Cinderella', the Victorian mouse society from 'The Great Mouse Detective', the modern one in 'the Rescuers', the Rescue Rangers, etc. - that they actually fit into quite nicely. So I'm choosing to assume that there are two distinct subcultures of anthropomorphic animals in the Disney universe - the human-sized ones, who are actually animal-shaped humans, and the itsy-bitsy ones, who are actual intelligent animals with a human-like culture. All the others are just normal animals. (And yes, I have thought about this far too much.)