Parthenogenesis, or "virgin birth," occurs in nature. Tityus serrulatus and Tityus columbianus, two species of scorpions from South America, often give birth to offspring without the participation of males. Rabbits and turkeys are sometimes said also to have partheogenic birth. However, it should be noted that all offspring of this type of "natural cloning" are female. Since there are only females giving birth this way, only females result. It also never occurs in higher animals like primates. The "Rabbit" level is about as high up the food chain as it gets. What would make the phenomenon of parthenogenesis miraculous is if it were to take place in primates, or if a male were to be produced by this method. Thus even though virgin birth takes place on rare occasions in nature, the birth of Jesus Christ is no less miraculous. A male human produced without presence of a human father is a spectacular miracle indeed. 

For information on parthenogenesis from a scientific point of view, see the following websites:   

Journal of Venomous Animals and Toxins: on the Parthenogenesis of Scorpions:

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-79301995000200002&lng=en&nrm=iso&tlng=en

A Guide to the Recognition of Parthenogenesis in Incubated Turkey Eggs from the Oregon State Univ:

http://oregonstate.edu/dept/animal-sciences/poultry/

encyclopedia.com on parthenogenesis in general

http://www.encyclopedia.com/html/p1/partheno.asp