When you see a late born fawn that still has spots during late fall or winter, it’s often difficult to figure out what was responsible for such a late birth. In many cases, does that are bred for the first time produce late born fawns because they may not reach puberty until January, February or March. An early or severe winter may also result in late born fawns as can hormonal problems and injuries among does.
I do know what is responsible, however, for the most recent case that I observed of a fawn that was born much later than normal. Apparently as does get old, there is a greater tendency of them having late born fawns, too. By old, I mean ages that few does reach such as 15 or 16. An old doe that is in that age bracket and lives at Marquette’s Presque Isle Park gave birth to fawns during August of 2014. This year, she didn’t have a fawn until September.
The fawns born during August last year did not survive and the chances of survival of the September fawn are not much better, unless the upcoming winter proves to be mild. The late born fawn’s summer coat won’t be warm enough to protect it from cold weather. The small deer won’t develop a fall coat of hair until December, if it lives that long.
The late born fawn’s small size and coloration also make it more vulnerable to predators. In the presence of deep snow, the small fawn would have more difficulty escaping predators than one born during June, which is when most Michigan fawns are born.
The gestation period for whitetails is seven months; so most does are bred during November. The doe that gave birth to the fawn in September had to have been bred in February. The year before, she conceived during January.
One other doe that is the same age as the whitetail that gave birth during September also had a fawn later than normal this year. She dropped a fawn during July. During her prime, that doe usually gave birth to fawns during late May.
Since last winter was easy on whitetails in the park and deer had access to a bumper crop of acorns, the weather would not have played much of a role, if any, in contributing to the birth of fawns later than normal for either doe.
The fawn born during July has a much better chance of survival than the one that began life two months later since it was only a month later than normal. In fact, the July fawn is doing well. It grew its fall coat during October.
Since I’ve been monitoring Presque Isle’s deer herd for many years, I know the reproductive history and fawn-rearing success of both of the park’s oldest does. The doe that gave birth to the fawn during September this year, for example, has not done well in terms of fawning rearing success. Prior to 2015, she only managed to give birth to fawns that survived during 2005 and 2006.
She had twins both years, consisting of one fawn of each sex. The bucks dispersed from the park as adults. Both of her daughters remain alive and reside in the park. They are 9 ½ and 10 1/2 years old.
Although the doe that gave birth to twins during 2005 and 2006 is normally pregnant, she has not given birth to a fawn that has survived since 2006. Coyotes have probably claimed some of the fawns that the doe gave birth to, but others that she had after rough winters may have been two small to survive when they were born. Stillbirths are common after severe winters in the UP and that’s why fawn production is often low after severe winters. Due to nutritional stress caused by long, cold winters, fawns usually don’t develop normally.
That doe’s 9 ½-year-old daughter is even less productive than her mother. She has not produced a single fawn that has survived during her entire life. She is usually pregnant, but none of the fawns she has given birth to, including two during 2015, have survived. Some does that have male twins, as this one did, sometimes end up with too much male hormones, and that may be what happened in her case.
Hormonal problems may inhibit this particular doe’s ability to produce milk for her fawns when she has them, reducing their chances of surviving. When she had her fawns this year, for example, her udder did not seem to be as full with milk as other does that had given birth. Hormonal problems may have also prevented her from becoming pregnant some years. During 2013, I saw this particular doe bred
on December 4 and then again on December 31. I’m sure she was probably bred during November, too, but she did not become pregnant.