Voyages of discovery? (spoilers for all RotE books)

[maulkin]

I'd assumed that the dragons kept their serpent memories, so they, too, would be in the ancient memories of the dragon race.

I don't think that they do. In Dragon Haven, when Kalo reveals the true identity of the Tarman he says something like "I do not remember much that I should and I remember much that I should not". He then goes on to describe events that occurred while he was a serpent in Maulkin's tangle. I took this to mean that adult dragons do not normally retain their serpent memories. In this case, the location of the serpents' feeding grounds may be known only to serpents.