Are coyotes really responsible for significant damage to deer herds, or do hunters and trappers simply have it out for these wild canines? Real research can answer this decades-old debate.
By Dr. Grant Woods
I was raised on a 108-acre farm in southwestern Missouri during the 1960s and ’70s. There were no or very few deer in the county where our family farm was located. But there were coyotes. I would hear them at night, see their tracks, and occasionally hear about a calf or chickens that had been killed by the coyotes.
Such losses were rare, as it was a rural area and coyotes were usually shot on sight. Many of the local folks would meet at a café for an early breakfast and determine where coyotes had been causing trouble. After breakfast, the men would cast (turn out) their dogs in the area where coyotes had recently been seen or where they had killed livestock, and the chase would be on! During most winter weekends, we would commonly see neighbors in their pickup trucks with dog boxes in the beds and CB antennas on the cabs, parked along our fence-rows. This happened weekend after weekend—for years.
At the same time, many locals trapped. Trappers recall the “fur boom” of the 80s. Fur prices reached an all-time high during the 1980s and many folks supplemented their income with raccoon and coyote pelts.
Coyotes ‘Back Then’There were always coyotes in our neighborhood, but their populations never built up very high. I left the farm during the late 1970s to go to college. There, I was taught that predators were in danger due to over-hunting, and that predators almost never have a negative impact on prey species (rabbits, quail, deer, etc.). I was also taught in Geology 101 that the next Ice Age was coming (I wish I had kept that textbook).
Predators probably were not having a major negative impact on prey species during that time. The rural nature of the society probably did a pretty good job of keeping predator populations in check. Even the grannies—like mine—were more than willing to grab the family’s sawed-off 12 gauge and make short work of any coyote they saw close to a chicken house. Those chickens were a source of food and income for the family, and critters that killed chickens were stealing.
I didn’t think much about coyote/deer interactions for years. After I finished college in Missouri, I worked in Nevada with mule deer during the summers where government trappers killed coyotes year ’round. They did it to protect livestock that were grazing on government land. Keeping coyote populations in balance with livestock and other species of wildlife was common practice in Western states at the time.
Then, I went to graduate school at the University of Georgia and Clemson University. There were no or very few coyotes in those states at that time. Seeing a coyote there was as infrequent as seeing a mountain lion in Missouri—very rare and almost never confirmed.
At one point, I was helping a fellow graduate student on a wild turkey project in the mountains of North Carolina. He was using game cameras to monitor how much turkeys used food plots in the mountains as part of his research. I clearly remember when he got a picture of a coyote; it was one of the first documented coyotes in North Carolina.
Deer Numbers Down: Coyotes To Blame?Fast-forward a couple of years. I had been working intensely on a whitetail project on 2,000 acres of private land in the mountains of northeastern Alabama. The deer herd responded well to the habitat improvements and deer harvest practices that I employed, which were designed to increase the herd’s health.
There were great food plots and extremely thick bedding/sanctuary areas. It was a deer and turkey paradise in the making! The hunters were happy and the deer herd was showing steady increases in body weights and fawn production, and other positive results were evident. Candidly, as the consulting biologist … I was cruising on easy street.
But then I received a call from the landowner asking some tough questions about a lack of deer sightings. I kidded him that he and his guests had gotten soft, and explained they needed to start hunting and stop being whiners. However, I quickly made a trip to the property to further investigate.
The food plots were in great shape. He had a complete record of soil-test results and how much fertilizer, seed, etc. had been used each year. The sanctuaries had not been violated by hunters. It was almost the same hunters on the property throughout the duration of the project. The land-management practices and hunter pressure had not changed on the neighboring properties. There was no obvious (at the time) reason for the deer population to have decreased or become less susceptible to hunters.
One observation stood out: I started noticing coyote scat along the roads.
I asked my friend and fellow wildlife biologist, Dr. Karl Miller, a professor at the University of Georgia, to tour the property with me. Karl agreed there was not any obvious reason for the deer population and quality of hunting to tank.
We decided to do a study and determine if by chance coyotes and other predators were impacting the deer herd. Cory VanGilder, a student who I had advised as an undergraduate and had much confidence in, was awarded a graduate assistantship funded by the landowner. Cory’s was tasked with conducting a detailed study of the deer population and the effects of the removal of predators on this property.
Determining Predator NumbersBeginning in October 2006, we analyzed predator abundance approximately every other month throughout the study. We did this by making scent stations in areas where we could identify tracks, and we searched the roads for predator scat. Any scat we found was removed so it was not double-counted.
Whitetail Fawn-To-Doe RatiosWe estimated fawn-to-doe ratios before and after predator removal using hunter observation data, camera surveys and Web-based camera observations. We selected experienced hunters (novice and youth hunters were excluded from data collection) who recorded all occurrences of deer observed during the hunting season (November to January in that part of Alabama). All deer observed were placed into categories including bucks, does, fawns and unknowns so we could estimate fawn survival.
Because fawns are easiest to distinguish from yearling and adult does early in the hunting season, we only used data collected in November to estimate fawn-to-doe ratios. These are ratios and estimates and not actual counts. Seeing the same deer twice does not reduce the accuracy of a ratio.
The study area contained 11 Web cameras (infrared cameras mounted on telephone poles that could be turned and focused from a computer), which were positioned to monitor food plots. Through an Internet connection, we could watch the plots 24/7/365.
We selected cameras at random to avoid bias and used them to monitor deer activity in food plots when deer activity would be greatest (early morning and late evening) during October, November and January (2006-2007—pre coyote removal; 2007-2008—post coyote removal). Cameras were viewed every day during this period, except in instances of extreme weather (lightning, etc.), which could potentially damage the cameras.
All deer were recorded and placed into categories (bucks, does, fawns) in the same manner as hunter observations. Most deer observed in the food plots could be positively identified by the Web cameras, which could pan nearly 360 degrees and zoom to 25X magnification. Individuals that could not be identified were categorized as unknowns.
We conducted game camera surveys during September 2006 and February 2007 (pre coyote removal) and September 2007 and February 2008 (post coyote removal). We used digital game cameras at a density of approximately one camera per 160 acres. To see the guidelines I recommend for conducting a game camera survey, click here to check out the guide.
We removed predators using a professional trapper during February-July 2007, prior to the 2007 fawning season. The trapper targeted areas we knew were frequented by coyotes and bobcats. Most trap sets were made along dirt roads, road intersections, trails or fire-breaks by using either a scent-post- or dirt-hole set.
Watch this video to learn more about trapping predators.
The Results Are InTwenty-two coyotes and 10 bobcats were removed from the farm prior to peak fawning during 2007. The average weight of coyotes was 31 pounds for males (12 total) and 27 pounds for females (10 total). The average weight of bobcats was 17 pounds for males (six total) and 11 pounds for females (four total).
Our research (scat counts, sign posts, etc.) all confirmed a decrease in coyotes and bobcats as a result of trapping prior to fawning. Scat deposition rates declined from a high of 1.6 scats per mile per day in January 2007 to near zero prior to and during peak fawning season. Pre-removal camera surveys indicated fawn-to-doe ratios of 0.18 during September 2006 and 0.41 during February 2007.
It was very exciting that following the removal of predators, the September camera fawn to-doe ratio increased to 0.24 (33.3 percent increase) and the February 2008 ratio increased 1.20 (193 percent increase)! Hunter observation data collected in November 2007 following the predator removal indicated the fawn-to-doe ratio increased 217 percent, rising to 1.11 fawns per doe.
Observations from the Web camera surveys showed the fawn-to-doe ratios increased an average of 156 percent between pre- and post-predator removal. Any way we looked at the data, the number of fawns significantly increased after trapping coyotes and bobcats on this 2,000-acre farm.
Similar results had been achieved on larger properties by researchers in Texas and Oklahoma.
Clearly, removing predators can increase the number of fawns that survive. We did not “scientifically” measure the increased pleasure of hunters on this farm, but I will report that they were very happy. Why wouldn’t they be? I like seeing deer and work hard to help folks grow healthy deer. Predators, especially coyotes, eat a lot of deer. They also cause deer stress. Stress can keep those deer from expressing their full potential in weight, fawn production, and—yes—antler size!
Does this mean I think all coyotes should be killed? Heck no. I enjoy hearing coyotes; they are part of the wild experience I crave. However, as a biologist and hunter, I know it is important for predator and prey relationships to be kept in balance. This rarely happens “naturally.” There are plenty of records of predators doing extreme damage to prey populations. Most hunters have heard about the substantial decreases in some elk populations, where the wolf populations have been allowed to go unchecked.
Where needed, hunters and trappers should be given the tools, seasons and necessary resources to help balance predator/prey populations. The relationships are not static. They change with time, and so should the seasons and tools we are allowed to use to manage their populations.
There were coyotes and bobcats in the county where I grew up. We enjoyed hearing and seeing them. Their populations were controlled but not eliminated. When the state restocked deer in that area, the herd expanded and thrived. It was not long before hunting was allowed and folks could recreate and collect some venison for their family. I can’t help but wonder: If the coyote population was as high then as it is now in many areas, would deer restocking efforts have been as successful? Granny’s 12 gauge, those farmers who coyote hunted, and high fur prices might have had more to do with the success of restocking deer than anyone ever credited.