Of all the questions I have received at this web site, this is the first
one I am going to have to say I do not know the answer. You ask a very
good question which is very difficult to know how to answer. Because you
ask the question, I assume you already see the difficulty of explaining
how the animals could have gotten to their present distribution in the
world if the only living species after the flood were in the ark. For
example, I see absolutely no way that a koala bear could migrate from
Australia to get on the ark, nor any way for the koala to make its way
back to Australia after the flood. It is simply impossible for koalas to
swim across open ocean. Besides, the land bridge argument definitely does
not work because there is no route from Asia to Australia which does not
involve crossing very deep ocean. I have thought of two possible
explanations of the current distribution of animals on the earth, assuming
the flood story in Genesis is thue, neither of which I can prove from the
Bible or from any other source of evidence.

1. One possibility is that after the flood, God miraculously recreated the
animals in places such as South America and Australia which were wiped out
in the flood and which obviously could not migrate to the ark to be saved.
By this picture, the animals on the ark with Noah and his family were
those which lived within some sort of reasonable distance from the ark.
Again, I cannot prove this claim and the Bible does not say that this is
what happened. I just believe it is a reasonable explanation of the facts
which would also agree with what the Bible says.

2. Another possibility is that when Genesis describes a world-wide flood,
it is indeed true that the world had a world wide effect, killing off
animals across the surface of the earth, but that the destruction was not
absolutely total–leaving at least some remnant populations in different
parts of the world. I personally do not like this explanation as well as
the first, as it calls into question at least to some extent some pretty
clear statements in Genesis chapters seven and eight which seems to
picture a flood which wiped out literally all creatures. However, I do not
think I can rule out this explanation. It is possible that God was
describing the flood in general terms, but not mentioning some details
such as some survivors in different places.

In the end, it is hard to make absolutely clear and unambiguous statements
in answer to your question. I suppose you can ask God in heaven if you are
there some day. By the way, there is a third explanation of the Genesis
account which is that it is just a myth and that one cannot expect it to
agree with what we know from science. I reject this view for several
reasons. First, the Bible has proven itself to be inspired by God through
such a massive amount of evidence that when I am confronted with a
question I cannot answer definitively, I give the Bible the benefit of the
doubt and accept on faith, based on the massive evidence of inspiration,
that the parts of the Bible I cannot prove by evidence are also inspired.
Besides there is some significant evidence that the flood described in
Genesis seven and eight actually happened. For a discussion of this, I
will refer you to another article at this web site. Just click on the
title Will it be Fire Next Time?

John Oakes, PhD