How is 'virgin birth' (aka parthenogenesis) considered a miracle? You find them in wide variety of species such as insects, crustaceans, rotifers, flatworms, snails, reptiles, sharks and birds. They don't occur naturally in mammals though, but it can be induced in mice, monkeys and rabbits (and in 2007 a human stem cell).
I think we've had this conversation before (on what makes a miracle a miracle). I'm not going to rehash that discussion. But to summarize, a miracle in the biblical sense does not have to be "supernatural" and some miracles in the Bible occured at least partly via natural processes. Primarily, what dostinguishes an event as miracle in the biblical sense is that it is a sign relating to salvation in some way.