What mechanism would you use to explain HOW these modern species came about from those few species that could fit on a boat?
Perhaps a better question is: how does the word "kind" relate to "species"? For instance, would all big cats be considered a "kind" in relation to the Hebrew language used in the Bible? Does "kind" allow for significant variations such that over even short period of time, interbreeding between isolated groups cannot occur? Did these changes in "kind" occur naturally, or by Divine intervention?
No, that is not a better question - it just further illustrates that Creationists are not comfortable with science and must invoke “Divine intervention” to explain just about anything of importance in the natural world.
So you have no mechanism that could explain it other than “Divine intervention”. You do know that this is not and never will be a scientific explanation, don't you?
Do you feel no need to come up with a scientific explanation to explain what you believe about the natural world?