C NATURAL DISASTER. Climate and weather are not so much of a problem because if the population is dense, then only the weaker ones will suffer and Darwin's "survival of the fittest" theory will occur, and produce more offspring with the genetics to survive climate and weather. Predation is not a problem because if the population is so dense, then there will always be enough to reproduce. Hover, natural disaster is the most devastating way to destroy or bottleneck a population because there is no chance they can adapt to it or avoid it.
