That is assuming that Mt. Everest had snow at all after the flood See this link http://christiananswers.net/q-aig/noah-above-mts.html
Which suggests that the origin of Everest is around the time of Noah's Flood and that since Everest's is currently rising at up to 15 centimeters (six inches) per year if you were to extrapolate backwards, "taking the rate of rise of 15 cm per year and the current height of Everest (8,848 meters, or 29,028 feet), Everest would have been at sea level only 59,000 years ago."
Some animals are so unique to their environment (see koala joke earlier in thread)
1. We do not know that the things that are UNIQUE to their environment were not there after the flood.
2. It is also possible that through degenerative mutation or loss of gene pool information the koala's descendants, who carry only a portion of that original gene pool of information, became more specialized and that their ancestors were more hardy. In other words, the koala's ancestor may have been able to survive on a much greater range of vegetation.