Every deer hunter knows the "rut" (mating) season is the best time to hunt whitetail bucks.

But most buck chasers believe this special time of the year only lasts a week or two during November. That belief is not exactly accurate, according to the North Carolina Wildlife Commission's top deer expert.

"The rut is no doubt the best time to hunt for bucks because they tend to increase their home range for a short duration," said Evin Stanford, the WRC's deer-project leader. "Bucks are looking for does and have breeding on their minds. So they're more vulnerable and not as wary because they're chasing does.

"They increase their range and are more active day and night."

However, Stanford said a savvy Tar Heel hunter with plenty of free time could hunt the rut for more than a month and maybe longer. But most N.C. outdoorsmen probably don't know the state has four "rut" periods, stretching from late October to the first week of December.

What's so special about the "rut" (deer mating season)? Well, it's the time bucks and does throw caution to the wind. For most of the year, except before the start of archery season, deer, especially bucks, are mostly invisible to curious human eyes. In the South, pressured whitetails prefer to stay within the safety of cover (deep woods, thickets, swamps) during daylight hours, An hour or so before dark in August, they'll begin to move toward feeding areas, often agricultural fields.

Deer wander, mostly at night during spring, summer and early fall, moving from food source to food source (check your garden, if you have one, for white-tail tracks made during the night). Just before dawn deer return to cover to rest, ruminate and await nightfall to repeat their feeding pattern.

Deer also segregate themselves - bucks with bucks and does with other does and fawns or yearlings - during the summer and early fall.

So seeing deer at any time during daylight hours is pretty rare in the South - except during the prerut, rut and postrut. But once the mating season cranks up, it seems as if the world is filled with whitetails.

During the rut, bucks chase does that are "coming into heat" (estrous) during a 24-hour span. Because the majority of does are ready to conceive during approximately the same few days each year, that period is known as the "peak" of the rut.

Although experts believe the "peak of the rut" (when the majority of breeding activity occurs) may not be the best time to hunt bucks, it's the time when most hunters will be in the woods. During the rut's peak, bucks remain with "hot" does for 24 to 36 hours, traveling only when they move. It's the seven days before (prerut) and after the peak (postrut) that usually produce maximum buck movements as mature males search for these does. So the "rut" actually is a three-week period (before and after the peak) at each of four sections of the state.

Starting in late October, whitetails are likely to wander into urban centers, residential neighborhoods and, most unfortunately, across highways, oblivious to people and automobiles (according to the N.C. Department of Transportation, deer/car collisions totaled 15,000 in 2005, most of them occurring during October and November).

But that wanderlust is also the reason the majority of bucks - including trophy-rack whitetails - fall to hunters during the rut.

Stanford and the WRC's biologists have known for some time the N.C. deer rut occurs at different times at different parts of the state.

"For the lower coastal plain, it's usually the last week of October," he said. "That means the pre-rut period (best hunting) is usually the third week of October.

"For the upper coastal plain, the peak typically happens the first week of November.

"For the piedmont and foothills, it's the third week of November.

"For the mountain counties, it's the first week of December."

Although hunters have had many theories about what triggers the rut, from moon phases to the first cold weather of the late fall, the real reason is the shortening of daylight as winter approaches. Somehow more darkness in each 24-hour period triggers hormones in bucks and does that tell them it's time to start making baby deer. The scientific term is photoperiodism.

So the big question is why do different rut peaks exist in North Carolina when daylight hours are identical from Murphy to Manteo?

"That's a good question," Stanford said. "There's never been any research done about it. It's just something that's been observed (in the past). Some people have suggested it's because northern deer were released in the western mountains at one time and spread east a little. But there weren't enough released deer to be a factor (for different rut peaks within North Carolina).

"We know it's related to the photoperiod, the shortening of daylight hours as we head into winter. People have experimented by putting deer in enclosed buildings and manipulating the amount of light they receive. They actually can create a 'rut' any time of year."

Stanford ruled out moon phases as a triggering mechanism for the rut because the moon's light cycle (from full moon to full moon) is 30 days in length. But because some months have 30 days, others 31 (and February has 28 days, except Leap Year), full moon dates during October and November may vary widely (during 2005, Oct. 17 was the full-moon date while Oct. 2006 had no full moon - its next occurrence is Nov. 5).

"If the rut was really related to the moon phase, you'd expect there'd be a wide swing in the timing of the rut, but that's not the case," Stanford said. "The rut occurs at the same period each year at given places. The timing of the rut occurs very consistently."

It's noteworthy the white-tailed deer rut begins earlier the farther north one goes and later the farther south. The Canadian rut can be going full bore by October while the rut in Texas and Mexico (closer to the equator means longer days in winter) typically happens in December.

Even so, many hunters believe the full moon near the end of October or start of November triggers the rut.

"(The four peak rut periods in N.C.) probably has something to do with available food (better-quality food means healthier deer) and weather," Stanford said.

Even though moon phases aren't a factor in marking the rut, hunters' "common knowledge" may be close to the truth when it comes to weather, although there's not a direct correlation between weather and rutting activity.

"Weather has nothing to do with the rut directly, but deer activity, or movements, are affected by weather," Stanford said.

As most dedicated deer hunters have observed, colder weather - with early-morning frosts and daytime highs hovering in the 40-degree range - usually begin early in November in North Carolina, falling well within the state's
1 1/2-month-long rut window.

With whitetails having insulated fur pelts, warm weather can make them uncomfortable if they move a lot, Stanford said. So during warm weather, deer usually remain in secluded areas - swamps or forests - to take advantage of shade. It stands to reason when temperatures drop, whitetails are more likely to wander, which makes them more likely to be seen by hunters. The onset of winter's colder temperatures usually occurs during the first two or three weeks of November which is, once again, inside the rut window.

Not only that, deer hunters probably are reinforced in thinking cloudy days result in more deer movement than bright days. That may be true because clouds keep sunlight from raising the air temperature, thus clouds mean colder days - and deer can move in comfort.

"Temperatures surely can increase activity of deer during daylight hours," Stanford said. "When it cools off, individuals may see more deer.

"When the (daytime) temperature gets into the 30s and 40s, deer can walk around more without getting too hot."

However, just because deer seem to move more when it's colder doesn't mean the weather caused the rut to kick in; it only means the rut coincided with cooler temperatures. The rut still will occur at the same time each year, cool weather or not. During recent years, Tar Heel hunters have continued to kill bucks that were chasing does the same weeks in October and November, even though the state experienced warm weather. It's just that when the weather heats up, more of the chasing and rutting behavior occurs at night when the mercury level falls.

In essence, deer don't postpone the rut just because it's hot outside.

However, one factor that can affect the length of the white-tailed deer rut is the sex ratio of the state's deer herd.

Biologists believe the closer a 1-to-1 buck-to-doe ratio exists, the rut will be of a shorter duration. That is, if a herd's male-to-female balance were evenly split, the rut would occur during a two-week period and every available doe would be pregnant when the fun ends.

Of course, that's not what happens.

Stanford noted if estrous does aren't bred by bucks during the first or "primary" rut, they'll come into heat again after 28 days, a time most hunters know as the "secondary rut." In North Carolina the deer mating season usually extends at least that long because there are more does than bucks; it's that simple.

However, even though many hunters complain the herd is unbalanced with too many does - which, ironically, extends the rut's length and increases trophy-hunting chances - Stanford said mathematically a herd's total sex ratio never can be more than three does to each buck (he includes button bucks into that formula).

"The problem is hunter selectivity," he said. "At the beginning of the season, the herd's closer to being in balance than it will be at any other time. But as soon as hunting begins, bucks get hammered (which creates fewer chances for does to be bred).

"During the rut, even more bucks are killed because they're chasing does, day and night, and they're easier for hunters to see.

"The best time to kill a buck is muzzle-loader season. That's buck-killing season because it usually coincides at each section of the state where the rut is occurring."

Deer normally stay within a one square mile home territory. But bucks, searching for hot does, will increase their range during the rut. If there are few does, bucks will range even wider.

Increased buck movements during the rut suggest a change in one traditional hunting tactic. Trophy hunters usually recommend not returning to the same stand repeatedly. They're convinced hunters leave their scent, which may alert bucks to their presence.

However, if there's plenty of buck sign (major scrapes, rub lines) and lots of does concentrated at a specific area, it's probably a good idea to place a stand nearby and hunt from that stand as much as possible during the rut.

Does will come to food sources (food plots or acorns) and, with bucks on the prowl, areas that attract does are likely to be visited by a mossy horn whose usual home range may be a mile or two down the road.