Gen 6:20 reads as follows in the KJV:
Of fowls after their kind, and of cattle after their kind, of every creeping thing of the earth after his kind, two of every sort shall come unto thee, to keep them alive.
The sense here is that the animals came to Noah, not that Noah went out and got each animal. I'm not sure that if I were a polar bear, I'd want to walk all the way from the polar regions to the ark, but if God is compelling the animals to come, then come they would have.