Is There Something Magic About Varys Spying Ability?

In A Game of Thrones Catelyn Stark swears Lord Varys knows things no man can know and that he has some dark art. Ned Stark dismisses this notion saying he only has spies, but by the end of the book Ned is asking Varys what sort of magician are you? When he gets a close up look at his disguise ability. So what is the truth? Does Varys have some dark art aiding his spying abilities or does he just have that many little birds?