White-tailed deer fawn births have been recorded every month of the year. And fawns born from a breeding in October are not that uncommon. Considering that even in a very balanced herd, 95% of breeding occur during a 5-to-6-week window. That leaves 5% for all sorts of odd times. And that's for a well-balanced herd, which not all areas have. While conducting research in South Carolina, on a very unbalanced herd, we found a breeding window of almost 125 days instead of the normal 35-40.