I personally think people are the biggest threat to large rabbit populations. Like the lads have said already on this thread, the other factors also see populations go boom or bust, but they do go round in cycles, seeing populations explode after a lot of years if left untouched.
You see keepered areas, and estates, where the rabbits are protected for a lot of years by the keepers from human pressure, the numbers can be unreal, although they will from time to time fall victim to mixi, and vhd which can near wipe them out, they get the chance to breed unhindered for quite a few years before th