Whitetail Breeding Dates by Latitude and State

STEP 1 · Three kinds of date

Conception estimates, peak collar movement and harvest dates tell you different things

The figures below use three kinds of measurement. Mixing those measures is how a trip ends up a week off. To estimate conception, researchers determine the age of a fetus or newborn fawn, then work backward. Texas Parks and Wildlife used fetal length to estimate breeding dates, assuming an average gestation of 200 days (TPWD report, 1996). In southwest Wisconsin, researchers used newborns' umbilical condition to estimate age, then worked backward by 200 days (Hunsaker and colleagues, 2025). Pennsylvania researchers measured fetuses taken from does killed on roads (Penn State researchers); the Illinois researchers measured fetuses from females they tested (Green and colleagues, 2017). GPS collars reveal the period when bucks cover the most ground. That movement peak relates to breeding, but it does not identify the date a doe conceives. Harvest measures use check-in totals, as the Ohio research later in this guide does. A county's harvest count alone cannot establish a breeding date.

Think of a mean or median as the middle of a spread. For adult does in Pennsylvania, annual medians during 1999 to 2006 ranged from 9 November to 16 November. Pooling the adults gave a median of 13 November; pooling the fawns gave 25 November (Predicting Rut Timing).

STEP 2 · Pennsylvania to Wisconsin

Breeding centers on early to mid-November; fawns lag by weeks

The weekly chart from Penn State helps explain the abrupt feel of mid-November. By October's final week, the females already bred made up about 20 percent. The share of all females bred during that final week alone exceeded 10 percent. The opening two weeks of November accounted for over 40 percent, and the bred share exceeded 85 percent by November's close. Some breeding continued through December and January, reaching even March. Duane Diefenbach attributes that tail to does whose first cycle passed without breeding and to fawns, which bred mainly during late November and December (The Delay of 2 Weeks).

Green's Illinois team tested 3,884 females. Pregnancy occurred in about 66 percent of them; the rate increased with age, from 20.5 percent among fawns to an adult rate of 85.8 percent. November marked the season's breeding high point. Estimated conception averaged 8 November among adults and 11 November among yearlings, compared with 2 December among fawns (Green and colleagues, 2017, published abstract).

Collar tracking offers another look at southwest Wisconsin. Researchers monitored 188 males fitted with collars in portions of Dane, Iowa and Grant counties over the observation period of 15 October to 1 December, 2017 to 2020. Using changepoint analysis to identify shifts in daily movement, they placed peak breeding from 23 October to 12 November. Across age groups and movement measures, starting dates ranged from 23 to 27 October, and ending dates ranged from 9 to 15 November. Movement indicated a peak lasting 20 to 21 days. Conception dates calculated backward from 307 of 347 captured newborn fawns indicated a peak lasting about 16 days. Mean hourly movement reached its highest level during the week of 5 to 11 November (Hunsaker et al. 2025). The collar window starts earlier than the measured mean conception date for adult females in Illinois (8 November) and the pooled median for adults in Pennsylvania (13 November). Differences in states and methods make this a rough comparison rather than a measured lead time. The pattern also agrees with Penn State's observation that male home ranges expanded in late October, when roughly a fifth of females had already been bred.

At South Carolina's Savannah River Site, farther south, Novak's team estimated dates of conception. Fall collections favored earlier dates, so the researchers corrected that bias. Adults alone averaged 13 November, with 15 days added or subtracted. The mean with fawns included was 20 November, with 27 days added or subtracted. Later conception among fawns pulled the curve toward later dates (Novak and colleagues, 1991, published abstract).

STEP 3 · Texas

Eight regions: breeding peaks range from late September to the week of Christmas

Over three years, TPWD studied 2,436 does across 16 research areas. The agency described that deer sample as the largest ever used for a breeding study in Texas. Yearly rut timing changed very little in most areas; timing across ecological regions differed (TPWD research).

Across the statewide doe sample, 92 were pregnant for every 100 examined. TPWD reported that the vast majority bred regardless of rut timing. Trans-Pecos had the lowest pregnancy rate at 81 percent; the agency reported drought there during the study's final two years. The rut occurred latest in South Texas. Even in that region, births preceded August: in the east, 90 percent were born by 19 July; the western area reached that birth share by 25 July.

STEP 4 · Mississippi and Florida

Within two states, peak breeding dates span August to February

According to Mississippi State's Deer Lab, breeding peaks range from late November in northwestern counties to mid-February in southeastern counties. Each region has a fairly consistent breeding season of about 30 to 45 days. Most breeding takes place during a 21-day period near the peak, followed three to four weeks later by a smaller second peak from does cycling again and fawns breeding (Ecology of the Rut). In their analysis of wild Mississippi populations, Dye and coauthors calculated an overall average conception date of 1 January and a standard deviation of 13.4 days (Dye et al. 2012, abstract).

An MSU Extension study using collars on private property beside the Big Black River set the peak rut window at two weeks, beginning 25 December and ending 7 January. Within that window, 50 percent of the does are bred. Another 20 percent breed during each two-week window on either side. Adult bucks at that site traveled about 4,800 yards daily in pre-rut. At peak rut, they covered over 7,500 yards daily (about 4 miles). In this dataset, the greater daily travel occurred during December and January rather than October and November (Publication 3927, Strickland and colleagues).

Florida's spread is even broader, with separate measurements for individual herds. Across four sectors, Richter and Labisky studied 380 does collected each month between July 1978 and January 1981. The mean dates for breeding were 10 August for Rotenberger, in Florida's south; 7 October for central Florida's Tosohatchee; 2 November for Camp Blanding, in the north; and 22 February for northwestern Florida's Eglin Air Force Base. The dates differed by up to six months (Richter and Labisky 1985, published abstract). An FWC bulletin from 2019 calls Florida's rut range the broadest among states. The range runs from July at Florida's southern extreme to early March at its northwestern extreme and in the Green Swamp Basin. Elina Garrison, an FWC biologist, said the agency's chronology research measured the gap between earliest and latest conception within each study area. Those gaps ran from 9 days to 110 days. Across areas, they averaged 45 days; most does bred within 60 days. In her view, hydrology seems likely to shape breeding dates in south Florida, though proving the connection is difficult. She described fawns born during the year's driest stretch, ahead of the wet season's June start. She added that restocking with deer brought from Texas, Wisconsin, Pennsylvania and Louisiana may contribute, though she considered it unlikely to explain the timing alone (FWC update dated 4 February 2019).

STEP 5 · Same latitude, different peak

Herds next door can breed a month apart

Latitude captures the broad pattern but falls short between neighboring herds. Sumners' team compared southern populations next to each other. Among six pairs, breeding dates were separated by 35 days on average; among four other pairs, the difference was 2 days or less. Mitochondrial DNA is inherited from the mother. It showed greater differentiation in the pairs with mismatched timing: an FST value of 0.408 versus 0.140 (P = 0.03). FST measures genetic differences among populations. Markers inherited through both parents showed no significant difference. Those findings point toward dispersing males maintaining connections between populations and toward maternal genetics affecting breeding dates. The authors propose that restocking and surviving local herds left this pattern. They say breeding dates may be fixed traits that managers must plan for (Sumners and colleagues, 2015, published abstract). According to MSU's summary, populations separated by under 30 miles can have breeding peaks spaced 30 days apart. Daughters' tendency to remain close to their mothers keeps that timing in place (Rut Ecology).

Age also shifts breeding within a single herd. Fawn conception was later than adult conception in Illinois (2 December versus 8 November), in Pennsylvania (25 November versus 13 November), and in the Savannah River sample. TPWD says a doe may not breed until the season's late stages if she is young or in poor condition. We interpret a northern herd's December "late rut" observation as something that can reflect fawns and does cycling again, even though most adults had bred weeks before. Changes in habitat or the herd can shift peak timing as well. For the mechanics, read day-length piece.

STEP 6 · Ohio harvest check

Central harvest timing shifted by days over 150 miles

The estimates discussed earlier describe conception or peaks inferred from collars. Our Ohio research brings in the third perspective, harvest timing. During the season, Ohio's required telecheck system supplies county harvest counts each week (Watching the Rut Happen). For The Rut Moves South, our analysis grouped 13 counties beside Lake Erie in the north and 12 beside the Ohio River in the south. The groups were about 2.5 degrees apart in latitude, a distance of roughly 150 miles. For each archery season in 2023, 2024 and 2025, we estimated its central harvest date from the average timing of reporting weeks 2 to 11. These are the season's second through eleventh weekly reports. A week contributed more weight when archery harvest was greater. In every season, the northern harvest center came earlier. The lead ranged from 1.4 days to 2.9 days.

Locations 150 miles apart within the same state showed a difference of days in the central harvest date. The Texas regions listed above differ by weeks, while paired southern herds can differ by a month. The Ohio number reflects harvest timing, not conception dates. Our paper says hunter effort, affected by weekends, weather and mast, confounds that result and warns against applying it outside Ohio.

STEP 7 · Field method

Build your hunting window around the closest measured herd's peak

These measurements support one planning conclusion: use a local date. Here is the process we follow.

We think hunters should use the closest measured herd to plan, because a statewide average is the wrong date for that job. For a south Texas hunt, we would not book from a Midwest calendar. Nor would we advise a Pennsylvania hunter to hold off until Christmas on the grounds that southern breeding happens late.

STEP 8 · Coverage and limits

The limits of these measurements

Sources here cover Illinois, Pennsylvania, southwest Wisconsin, South Carolina's Savannah River Site, Mississippi, Texas and Florida. For Georgia, Alabama, Louisiana and other places, hunters should seek breeding chronologies or fetal research from their own state wildlife agencies. Some samples are old: the Florida collections ran from 1978 to 1981, and South Carolina's ran from 1974 to 1984; the TPWD account was written in 1996. Changes in herds or habitat can shift the peak. The methods also vary, using fetal lengths, births traced backward and collar changepoint analysis. Start comparisons with results collected by the same method. Results from Dye, Green, Sumners and Novak, plus Richter and Labisky, were reviewed in published abstracts.