The timing of the whitetail breeding season is set by shortening days in autumn; in other words, changing photoperiod. Hence, whitetails are considered “short-day breeders” in that a decreasing ratio of daylight to darkness in autumn causes their glands to secrete hormones that start their reproductive cycle and trigger sharp changes in their behavior.
Clearly, timing of the whitetail rut is highly adaptive in that it assures the majority of does give birth during spring when food and cover conditions are most favorable for rearing young.
North of about 36 degrees latitude, most whitetails breed between mid-October and mid-December, with peak breeding occurring during November.
When conception records of individual does are graphed, some biologists say the data should follow a normal, or “bell-shaped” curve, if the given population is nutritionally and socially healthy. That is, while most does breed in November, relatively few, but roughly equal numbers, of does are expected to breed early and late. I disagree with that notion.
Instead, I argue the typical rut pattern is skewed to the right, or late season, even in healthy Northern deer herds.
Since start of the rut is set by decreasing photoperiod — a consistent and reliable trigger — seldom if ever is the pattern of breeding heavily skewed to the left, or early season, in wild populations.
Almost invariably, the Northern rut starts with a sudden burst of breeding activity, reaches a peak, then gradually subsides with a trickle of late-breeders, even into January and sometimes later, extending the right tail of the rut season curve.
The number and timing of late breeding does will depend
