So something just crossed my mind when seeing a new video game trailer about the Norse settlement in Vinland, and seeing a character on a donkey made me wonder, "Were any livestock remains found, and did any escape into the new world creating a new population?"
I don't think I ever remember hearing anything about that, but it makes one wonder if there were such a thing like that possibly that could have happened like when the Spanish Pigs and horses and cattle escaped into North America creating wild populations of animals such as the wild Feral Pigs, Mustangs or Texas Longhorn.
Nope. Some seal and whale bones were found, but no livestock bones. The site was exposed and would have been poorly chosen for livestock farming. There were no barns, and archaeological testing found no trace of enclosures. There also weren't any disturbances of plant-life which would have been caused by grazing (or cultivation).
So the lack of animal bones is one of many indicators that the Greenlanders who set up shop at L'Anse aux Meadows didn't bring any animals with them. Overall, the archaeological finds from the site suggest they were never planning to stay long-term. Despite a silly saga account of a cow and a woman terrifying Native Americans with her breasts (see ch. 12)—which is too good a story to believe—they appear to have brought neither livestock nor women with them, and when they left, it was a well-organized affair.
If you're interested in the site, check out Birgitta Wallace, The Norse in Newfoundland: L'Anse aux Meadows and Vinland, Newfoundland and Labrador Studies 19.1 (2003), pp. 5-43. [Also available as a PDF]