Whitetail Deer Breeding - When and Why

White-tailed deer breed during the fall of each year. The deer breeding season is a special time of the year that is commonly referred to as the "rut" by deer hunters. Hunting during the rut increases a hunter's chances of seeing bucks because they are actively moving around, searching for receptive does that have come into estrus. Whitetail does are seasonally polyoestrous and usually come into heat for a short twenty-four hour period. If a doe is not mated (bred), a second estrus occurs approximately 28 days later. Bucks are polygamous and research has found that very few does go unbred, even when buck to doe ratios are highly skewed towards many more does than bucks.

Whitetail breeding occurs from September to January. The onset of the breeding season as well as the peak of the rut varies locally. Over time, whitetail deer have developed natural cues to ensure fawns are born at or around the ideal time of the year.As whitetail have evolved the deer breeding season has been sculpted by natural selection; the survival of the fittest. A well timed whitetail rut results in a high fawn survival rate as well as the survival of the species. Individual deer that successfully breed, produce and recruit offspring into the deer population pass on their genes for similar behavior. In this manner over time, the local deer breeding period is established.

The environmental conditions that impact habitat conditions are fairly stable from year to year, but not always predictable. Fawns born too early in the year may be susceptible to cold, harsh weather. A late spring green-up means limited foods for lactating does. Fawns born too into summer may not have adequate time to increase their body size and build strength for winter.

Whitetail Breeding - Gestation and Fawn Survival

In early summer, after a gestation period of about 200 days, whitetail does give birth to one or two young. Fawns weigh 5 to 8 pounds at birth, but quickly gain weight. They are able to walk at birth and can run within a week. Fawns will begin foraging on limited vegetation when only a few days old. Cared for only by the doe, fawns are nursed for about 10 to 12 weeks before weaning. The majority of fawns will be weaned prior to the fall deer hunting season.

The fawning period for deer found in an area/region remains consistent from year to year. However,studies have found that enivornmental cues definitely play a role. The amount of daylight is an important cue, but food and temperture also come into play. Deer breeding is not just genetically determined. Does can change, though probably not conciously, when they come into estrus. Whitetail that are moved from one region to another will adapt to the new breeding window.

White-tailed Deer

White-tailed deer are the smallest members of the North American deer family. Whitetail are found from southern Canada to South America. They are an important part of the landscape in all areas where they are found. During summer months deer often use fields and meadows, searching for forbs high in protein, but whitetail deer are primarily browsers. Read more...

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