Buck Use of Scrapes — What the Latest Research Reveals
By: Karen Alexy
It is always exciting to walk through the woods on a cool fall morning and discover a well–worked scrape. Maybe we envision a mature buck vigorously pawing the ground and raking his antlers through the overhanging branches. Because of this, deer hunters often hunt near these scrapes, hoping to catch a glimpse of the animal that produced it.
Traditionally, it was believed that scrapes were used by mature bucks to locate does. The dominant buck would create a scrape, and then an estrous doe would visit the scrape and leave her scent by urinating in the pawed area. The buck would then revisit his scrape and follow a scent trail to the receptive doe. Given this information, hunting over scrapes during the rut appears to provide a good opportunity to harvest a mature buck. However, two years ago I reported in Quality Whitetails on the results from the first year of a study conducted at The University of Georgia that caused us to reconsider many traditional beliefs about scrapes. Since then, we have completed another year of research, and the results reinforced our findings from the first year.
Previous Scrape Research
Past research indicated that scrapes function as signposts, containing signals that can be detected by other deer through vision or olfaction. Additional studies revealed that scrapes are created and maintained by dominant bucks and likely communicate information to other deer such as dominance status or reproductive condition. These past studies have shown that yearlings and 2.5–year–old bucks rarely mark scrapes and these behaviors are delayed until later in the season. They found that subordinate bucks may mark overhanging branches, but rarely paw the ground or urinate, and that older bucks may actually suppress this behavior in younger, less dominant bucks. Furthermore, it was believed that only one buck would work any particular scrape. While this research provided valuable insight about the function of scrapes, many of these conclusions were based on studies of captive animals. There are unavoidable biases associated with captive studies since the animals are confined and observations are limited to daylight hours. Another method used for monitoring scraping behavior is through motion–activated still cameras. While this technique provides valuable nocturnal data and pictures of deer visiting the scrape, it is nearly impossible to determine behaviors associated with the pictures.
The Georgia Study
In early October 1997, we began a research project focusing on the scraping behaviors of a wild population of white–tailed deer. We employed a technique using motion–activated video cameras that allowed us to observe scraping behaviors 24 hours a day. The set–up consisted of an 8mm video camera, a passive motion–activated trigger, a 75–watt floodlight (powered by a 12–volt battery) covered with a red lens and a waterproof enclosure (5 gallon bucket). When movement occurs in front of the unit, the camera records until the animal leaves the area. The light is programmed to turn on during evening hours, and the red lens is used to minimize deer disturbance.
During this two–year study, we monitored six scrapes per year on a 3,460–acre study site in Madison and Oglethorpe counties in northeast Georgia. These properties have been managed under a Quality Deer Management program for the past 11 years. Therefore, young bucks are protected and doe harvest is liberal, resulting in a population with a nearly balanced adult sex ratio and numerous mature bucks. Deer densities for these counties are about 40 deer/mi2, and most breedi
ng occurs during the first two weeks of November.
In late September 1997, we located six traditional scrape sites that had been used during previous breeding seasons. We placed four units along field edges and two in forests. We recorded behaviors at the scrapes from 7 October 1997 to 21 February 1998. Monestimate their age.
The results obtained from this two–year study were surprising. First, we found that 85 percent of all scraping activity occurred at night (Fig. 1). This was true for both the scrapes along the field edges and those in the forest interior. White–tailed deer are typically considered “crepuscular” or most active during early morning and late evening. However, as you can tell by the graph, bucks are active throughout the night with very little scrape use during daylight hours. In addition, overall scrape visitations were relatively low (remember that the units recorded 24 hours a day for the entire season). On each scrape, there were only a handful of opportunities to encounter any bucks during hunting hours.
Previous research on captive animals indicated that only the dominant buck in an area will perform a full series of marking behaviors, including overhead branch marking, urinating (normal or rub–urination), and pawing. However, our data show that many bucks will work the same scrape (Table 1). Although many different bucks may work scrapes, overall scrape use does not appear very intensive. Even more interesting is that many of these animals are yearling bucks. Therefore, there doesn’t appear to be a suppression effect from dominant animals. Also, yearlings worked the scrapes with the same intensity as older bucks, and many of the marking events were concurrent with those of older bucks.
Of considerable interest to the hunters on the property was that almost none of the mature bucks (3.5 years old or older) harvested on the property during the two years of the study were ever captured on video. This is even more interesting given that several of these bucks were harvested within a few hundred yards of a monitored scrape. This suggests either that mature bucks can obtain information from scrapes without actually visiting them (e.g., monitoring them from downwind) or that they avoided the scrapes due to the monitoring equipment. It is believed that the monitoring equipment was not responsible for their avoidance since researchers checked them only once every one to two weeks. Also, the harvest of several mature bucks in close proximity to the monitored scrapes would indicate that they were not actively avoiding the monitored areas.
The most frequent marking behavior performed by all ages of bucks was overhead branch marking. Nearly all signposting included bucks marking overhanging branches with their foreheads, antlers, or saliva. Pawing the ground and urination occurred in less than half of visits that included some type of marking behavior. Possibly, the scents deposited on branches may provide important chemical signals for communication between deer. Additionally, in early October most scent marking at scrapes consisted of branch marking and/or urination, but not pawing. Therefore, scrapes likely are being visited by bucks and relaying information before the physical evidence of pawing is observed.
We also examined the seasonal use of the scrapes (Fig. 2). The peak of the rut in the Georgia Piedmont typically occurs during the first three weeks of November. Marking by all ages of bucks occurred almost exclusively during October and November. Marking dates by yearlings coincided with the older deer, and marking wa
s not delayed until later in the breeding season. Therefore, these behaviors do not appear to be suppressed by dominant animals, which is commonly seen in penned studies. Although almost all marking ceased by late November, bucks still visited and investigated scrapes through December.
In our study, does frequently visited scrapes as well. We were not able to collect as much information on does because we were not able to distinguish individuals. However, the daily use of scrapes by does was very similar to the patterns seen in bucks. They also were primarily nocturnal, and visitations occurred primarily during October and November. Does not only investigated scrapes, but several were observed marking overhanging branches with their foreheads and saliva. Other studies documented urination in scrapes by does; however, this behavior was not recorded during our study. The frequent visitation to scrapes and occasional branch marking suggests that does could be receiving breeding information about bucks, as well as depositing scents.
During this two–year study, certain scrapes were much more active than others. Some scrapes had visitations by as many as 13 different bucks, whereas others had visitations by relatively few bucks. In either case, this would cast doubt on the theory of a scrape line being created and maintained by a single buck. In fact, despite two monitored sites being less than 300 yards apart, two completely different groups of bucks were using each scrape. Only one buck was monitored at both scrapes. These differences may be attributed to the location of the scrapes. Some scrapes were located in forested areas, while others were along field edges. Areas surrounding some scrapes may have provided better cover, food, or other necessary resources, and therefore, influenced visitation. However, one scrape that was monitored during both years was frequently visited the first year but visited little during the second year. Therefore, some other factor(s) could be responsible for differences in the use of scrapes. During the second year, there was an acorn mast failure in the region. This failure corresponded with a reduction in scraping activity. It is possible that intensity of scraping activity shifted with food availability. In other words, bucks may have shifted their core home ranges to areas where does were drawn to food sources.
Conclusions and Hunting Implications
This study provided new information on the scraping behaviors of wild white–tailed deer. We observed that scrape use is primarily nocturnal and highly seasonal, with most visits occurring 2–3 weeks prior to the rut. After the peak of the rut, bucks almost completely stop visiting scrapes. We also found that yearling and 2.5–year–old bucks mark the same scrapes as older deer, and marking behaviors by younger bucks are not delayed until later in the season. Although bucks may frequently investigate scrapes, the frequency of marking behaviors appears relatively low. This implies that chemical signals may be persistent, and that repeated marking is not necessary.
Because most visits occurred at night, marking was relatively infrequent, and mature bucks were not commonly observed, it might not be advantageous to hunt scrapes. Given this new evidence, concentrating hunting efforts on bedding sites, travel corridors, or feeding areas may be more advantageous. Since frequent scrape activity occurred just after dusk, hunting trails leading to and from scrapes might be an effective way of using these signposts to increase harvest opportunity. With this research and other projects at the University, we hope to learn even more about the role of these signposts in whitetail communication and behavior.
Karen Alexy received both her B.S. and M.S. degrees in wildlife biology at The University of Georgia. She currently is working toward her PhD at Clemson University and is currently doing deer research in conjuncti
on with the State of Kentucky.
itoring for the second year began on 27 August 1998 and ended on 6 February 1999. Antler and body characteristics were used to identify individual bucks and