However, the article is talking about a specific claim that they would also be more intelligent. This is a far harder hypothesis to predict the truth of (and to test). But, to the extent that "intelligent" is well defined it is still a reasonable hypothesis to have. In fact, I think that, by far, the least likely scenario is that they are equally as intelligent as their rural counterparts, as that would mean that environment has no effect on their intelligence. While this is probably true of some animals, It would be very surprising to me if it held for the more cognitive ones. The question then becomes how big of an effect is it, and in what direction.

Of course, when we drill into what "intellegence" means, we will probably find that it is a multi-dimensional notion, and refine the discussion to more/less intelligent in certain dimensions.

EDIT: it is also conceivable that an animal that grew up in environment A, then moved to environmnet B could be better suited for environment B than the one that had lived in B for its whole life.