Help me defend Noah's Flood

Hello there!

I have recently got into Christian apologetics after moving to a big city for my new job. Boy, does everybody have an opinion here! There are quite a few atheists in my community, though most are Christian (or say they are). However, even the Christians question the truth of the Bible, and I frequently have to defend myself from philosophical attacks. I was hoping you could help me come up with rebuttals to some of their arguments.

Here, for example, is an argument a colleague presented to me the other day to refute the story of Noah and the Great Flood. He argues that the Flood can't be true because there are no kangaroos in Turkey. He argues that if the Ark landed on Mount Ararat in Turkey and unloaded its cargo of animals, there should be a population of kangaroos native to Turkey, because there should have been a pair of kangaroos on the Ark. He says that that pair of kangaroos couldn't have traveled all the way to Australia from Turkey; they would have starved to death or something. I told him that God might have helped them along, but he accused me of "plugging a hole with more miracles". I don't know what to say to him now. If I say he is being deluded by humanist scientists he gets mad at me. How can I respond?