November 04, 2010
By C.J. Winand
Remote trail cameras give researchers and hunters new insights into deer behavior at scrapes.
By C. J. Winand
In 1952, William Pruitt published the first scientific paper to reference scrapes. Since then, whitetails have become the most studied animals in the world. Yet, can all the research and knowledge help you kill more deer at or near scrapes? Can scrape research help increase your odds of taking quality bucks?
A scrape is a signpost with the overhanging branch being the key. Without it, visitation rates drop exponentially to almost zero. Some biologists believe a scrape also has the ability to transmit the individual identity of a specific buck. Research has also shown that 85 percent of buck visitations occur at night.
To answer these questions I pondered what we -- hunters and biologists -- used to believe about scrapes. For years, we thought scrapes were actually defended by a specific buck. Our rationale was simple: Because a dominant buck would paw out the scrape, urinate in it, and mark an overhanging branch, inferior bucks would not re-mark the existing scrape or challenge a superior buck. In short, many of us believed that a scrape was part of a buck's territory. Nowadays, we know bucks are not territorial -- unless they are on the tails of estrous does.
We also know that totally different bucks might use two scrape lines only 100 yards apart. And just as their rub-making skills may differ, some bucks are good scrapers while others are not. Some biologists have also suggested that does can tell the breeding or social status of a buck from the smell of the scrape or overhanging branch.
What Defines an Active Scrape?
Many outdoor writers have suggested there are two kinds of scrapes: primary and secondary. By their definition, primary scrapes are located in the same location year after year, directly under the same overhanging branch. Secondary scrapes are generally found along well-used trails leading to feeding or bedding areas.
I don't really subscribe to those definitions. I'd argue that whatever the size, a scrape is active if it has an overhanging branch. That's because an overhanging branch acts like a telephone receiver, and without it the telephone is obsolete. The key to any scrape visitation is the presence of an overhanging branch. I'd go so far as to suggest that if a scrape does not have an overhanging branch, it's useless and best left behind.
Do Bucks Revisit Scrapes?
With the advent of trail cameras, part of the mystery about scrapes is now being answered. Wildlife biologist Karen Alexy found that half of the bucks she videotaped revisited a specific scrape, but only a handful visited more than one of her monitored scrapes. Other studies show that no bucks revisited the same scrape. As many hunters know, bucks check scrapes remotely from downwind. Does wind-checking of scrapes play a more significant role than we think? Apparently so.
Does Human Urine Pollute a Hunting Area?
Years ago Dr. James Kroll and Ben Koerth used remote cameras to monitor scrapes treated with buck urine, estrous doe urine, human urine, and nothing. Interestingly, they found that bucks regularly visited the scrapes treated with human urine. That's one reason that, nowadays, I commonly relieve myself in existing scrapes. Yes, you read that correctly. And if I'm out of "juice," I convince one of my hunting partners to doctor the scrapes for me. Granted, this may seem unorthodox, but more times than not the scrapes will be worked over by bucks (primarily at night).
Okay, then, does urinating in your hunting area decrease the sightings of mature bucks?
No way. My cameras pick up the same percentage of bucks visiting scrapes whether I urinate in them or not. Scrape visitations have one common denominator -- they take place mostly at night.
Whenever leaving a hunting area, I regularly use my boot to make a mock scrape or two under an overhanging branch and urinate in it. Why is it important to create such mock scrapes? Simple. If a buck walking by your stand gets preoccupied with one of your scrapes, you have a better chance for a shot.
Even if urinating in your area is contrary to everything you think about deer, making a mock scrape under an overhanging branch without any type of urine will also work to attract bucks. The need to add urine (human or deer) or transfer soil from an existing scrape to another is definitely not necessary to attract bucks.
What Role Does the Overhanging Branch Play?
Researcher Jason Braun observed that yearling bucks marked the branches overhanging scrapes 40 percent of the time. This percentage apparently increases with age, as Braun observed that 4½-year-old bucks marked the branches 63 percent of the time. The exact chemical signal and the importance of the preorbital gland (corner of eye) or the forehead gland are still unknown. Since older bucks seem to mark the branch more frequently, maybe it's a way to leave their calling card?
Whatever the case, both these glands transfer some kind of communication at scrapes that all deer use. Collecting the wax-like substance in the corner of the eye or cutting off the skull plate between the antlers is an excellent way to make your own scent. As with any scent, refrigeration and freezing help preserve the scent between uses.
Many hunters don't realize that when a buck rubs urine over his hocks it causes the tarsal hairs to retain specific lipids that retain odors. This is why some biologists believe that other deer can identify specific bucks that previously marked scrapes.
Should You Hunt Over Scrapes?
Research has shown that bucks go through the full scraping sequence -- marking the overhead branch, pawing the ground, and urinating over the tarsal glands -- occurs in less than four percent of all visits. Smaller bucks will not mark or rub-urinate in a scrape when a larger or dominant buck is in the vicinity. Karen Alexy reported that older bucks perform full scraping sequences twice as often as yearling bucks do.
Wildlife researcher Dr. Grant Woods found that most of the bucks he has pictures of visited scrapes during the night. However, some did visit scrapes during daylight hours, and the most activity took place from 8:45 a.m. to 10:15 a.m. Chances are you can relate to this and remember when you vowed to sit over a scrape until Mr. Big showed up. But he never did. Was Mr. Big wind-checking the scrapes? Maybe?
Georgia research has shown that 85 percent of buck and 75 percent of doe visits at scrapes occur at night. This is the main reason I've all but abandoned scrape hunting. I'd go so far as to say that hunting over scrapes is a waste of time. Granted, my hunting may be different from yours (yes, I hunt pressured deer), but the scrape research is cle
ar: Bucks visit scrapes primarily at night.
Jason Snavely, a wildlife biologist with Droptine Wildlife Consulting in Pennsylvania, has used cameras for 10 years to monitor deer activity at scrapes, and his findings parallel those of Dr. Woods. Snavely said, "Overall, my buck visitation at scrapes is 90 percent nocturnal. But, now that I've significantly cut down on pressure and increased the number of mature bucks, I've noticed that bucks will frequent scrapes along field edges during the first hour of legal shooting time during the early bow season." Snavely believes the key to hunting scrapes is to strictly limit hunting pressure and focus on early morning hours.
In addition, Bowhunter's Conservation Editor Dr. Dave Samuel reminded me that, in areas with good buck/doe ratios and lots of older bucks, data show that rutting bucks do visit scrapes during the day. For example, in a Texas study conducted where bucks are not shot until 5½ years of age, cameras showed that almost half of bucks over 4½ years of age came to scrapes during the day. Of course, in most deer herds, less than five percent of the bucks reach the age of 4½ years. Still, maybe they do where you hunt. If hunting pressure there is light, scrape hunting may be productive for you.
C.J.'s Summary: Like rubs, scrapes convey visual and olfactory signals among deer. Yearling bucks definitely are more vulnerable at scrapes during daylight hours, and if these deer are your goal, hunting scrapes may be a good strategy. But if you're targeting older deer, hunting over scrapes during daylight hours is generally fruitless unless your area receives very little hunting pressure.
For more information on scrapes and other biological data on deer behavior, I recommend Dr. Dave Samuel's new book, Whitetail Advantage. To order, go to www.knowhunting.com.