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New Road-Kill Rut Map Explained

Research shows a correlation between deer-vehicle collisions and deer movement during the peak rutting times.

JOINT | November 3, 2014

Editor’s Note: The following article and accompanying graphics were developed through research after a collaborative effort between the UGA Deer Lab, WRD and Georgia DOT.

Peak rut is that magical window of time when most hunters would like to be firmly planted in the deer woods. Unlike their northern brethren who breed primarily in November, Georgia deer have a more variable breeding calendar that ranges from October in some parts of the state through December in other regions.

This is a result of fewer environmental extremes and possibly because Georgia deer are a melting pot of subspecies from restocking efforts.

So what is the “rut?”

The rut is essentially several phases of courtship and breeding behavior throughout autumn; of particular interest here is peak seeking and chasing activity. Peak seeking and chasing, the aforementioned magical window, occurs during a narrow time period when most bucks are searching for does in estrus and chasing the many of does they encounter.

While a substantial percentage of does may be bred during a peak week, breeding activity may last for more than a month, and bucks may be observed chasing does outside the peak for any given location.

When is peak rut?

Knowing when the peak of the rut occurs can improve hunter efficiency, opportunity, success and overall satisfaction. After all, planning vacation time to coincide with peak rut is an annual ordeal for many deer hunters, and it is especially important when hunting a new property for the first time.

Historically, biologists determined when the peak in conceptions occurs by estimating conception dates from fetuses obtained from bred females. To do this, fetuses are collected from does harvested late in the season and measured on a scale that is calibrated to back-track to the date of conception. Unfortunately, this method is labor intensive, site specific, and often cannot be conducted during the regular hunting season. Depending on where you hunt, the season may end before fetuses reach 35 days old, which is the minimum age at which the fetal scale is accurate. Keeping hunter-observation records can also be useful to estimate peak deer movement, but it often takes several years of data collection before patterns emerge. Again, observations of bucks chasing does is not necessarily an indication that peak rut is occurring.

Due to the difficulties in accurately determining peak rut dates, an alternate method would obviously be very useful. Numerous deer-vehicle collision (DVC) studies have reported increases in DVCs during periods of increased deer movement. This led us to investigate the possibility of utilizing historical DVC data collected by the Georgia Department of Transportation (DOT). We used data collected from Sept. 1 to Jan. 31 from 2005 to 2012 to create a map displaying the peak week of DVCs in each county of Georgia.

To test the accuracy of our map for predicting the rut, we compared the occurrence of DVCs against conception dates in three Georgia counties. In these counties, the occurrence of conceptions and DVCs were almost identical (see chart on page 18). Fortunately, we also had a large data set of movement data from 19 GPS collared deer (10 bucks and nine does) in Harris County. Movement rates from these deer peaked at the same time as DVCs and were concurrent with increased numbers of conceptions. Of further interest, buck movement rates were driving the peak in movement activity. If bucks drive the deer movement activity during the breeding season, and if DVCs are an index of deer movement activity, then our map of peak DVCs likely represents the peak in buck movement activity.

Our road-kill rut map appears to be an accurate predictor of the timing of the rut at the county-level. However, we do know that the timing of the rut can vary locally to some degree based on deer sex ratio and age structure. Nevertheless, this map is based on empirical data, and it can be updated annually to increase accuracy. DVC data is readily available in large quantities for multiple years over large areas, and it’s available to us at no additional expense to Georgia hunters.

An additional benefit of the map is that it can be used as a warning system for drivers to be aware of peak deer activity. With an ever-increasing number of cars on the road, collisions with deer are inevitable. The ability to better predict peaks in deer movement, combined with novel fencing designs to deter deer from crossing roads, can help protect Georgia motorists.

An interactive version of the map is hosted on the web by the Georgia Wildlife Resources Division (www.gohuntgeorgia.com/rut-map). Development of this map was a collaborative effort between the University of Georgia’s Deer Lab and the Georgia Wildlife Resources Division. We hope you find Georgia’s new rut map to be a useful resource, and we wish you all a fun and safe hunting season.

We thank the Georgia Department of Transportation for providing deer-vehicle collision data and for funding this study. The Georgia Department of Natural Resources: Wildlife Resources Division, Callaway Gardens biologist Cory Croft and the USDA Wildlife Services provided conception data.

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