They are not indigenous to that country.
Consequently, they had no predators. They had plenty of grass to eat.
Their reproductive rate is again approximately constant.
There was no migration
So again, we had a situation where the assumptions were upheld.
Again the rabbits population grew exponentially. There was a plague of
rabbits.
So much so that they had to introduce a genetic defect to control the
breeding. This then made rabbits unfit for human consumption.
A sad case of ecological mistakes.