"baby animals wouldn't take up as much space."
True, but you still don't have a good grasp of how many, many animals would have had to be accommodated. Then there would also have been their food, water, and bedding. Waste removal and ventilation would have been impossible on this 3-deck barge with only one small window which was most often closed.
"God may have put them in a deep sleep - hibernation."
Well, if we are going to take that route, the omnipotent God could have just killed everything he didn't like with a word, eliminating the need for an ark or a flood. God could have transported all the "good" people and animals to the moon in a big bubble of air and then brought them back when the earth was safe again. The problem with having God solve a problem by way of a miracle is that it doesn't really explain anything.
"He did it to Adam,"
"He can do it again."
Uh huh. Says you, again.
"We call it local anesthesia."
No, Dumdum, that would be called "general anesthsia."
Remember - If you don't know what your talking about, SHUT UP.