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The Coyote Factor Taking a Bite Out of Deer
Research sheds light on the impacts of coyotes.
By Charlie Killmaster, Wildlife Biologist
Originally published in the July 2010 issue of AON
The Southeast offers a cozy life for coyotes abundant fruits and small mammals, heavy cover and little competition for resources. These comforts allow coyote densities in the Southeast to exceed those in the West.
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Many hunters have all been told at one time or another that coyotes don’t really have a major impact on southeastern deer populations. I wouldn’t doubt you may have heard it from a wildlife biologist. For many years, coyotes were generally considered insignificant regarding their affect on deer populations. But, as we all know, things change, and wildlife ecology is no different.

Rewind 40 years to the tail end of deer restocking in the Southeast. Deer predators were virtually nonexistent, save the occasional bobcat that escaped the once-booming fur market. Deer management was centered on increasing population density where deer remained, and restoring populations to areas lacking deer altogether. Southeastern deer had it easy back then with restrictive seasons and bag limits, very few predators and mild winters.

By the late 1980s, deer populations responded accordingly; so well in fact, that many state wildlife agencies were scrambling for longer seasons and increased bag limits to keep deer from eating everything within 5 feet of the ground. Around this same time, a new pack of hunters started moving in from the West. Unfortunately, these hunters, of the four-legged variety, weren’t required to pay non-resident license fees like other folks from out-of-state.

Coyote populations, particularly over the last decade, have grown exponentially in many southeastern states. In Alabama, coyotes are found in every county of the state including many metropolitan areas. According to Chris Cook, Alabama Deer Studies Project Leader, coyote harvest has quadrupled since 1990.

So, how did coyote populations grow so rapidly? Through a combination of natural range expansion and escaped captives (some unintentional, some not), coyotes began their eastern march. Coyotes, much like deer, are very adaptable animals that can thrive in a variety of landscapes. Unlike some other large predators, they can be very tolerant of human activity and may actually have an affinity for a suburban lifestyle. The Southeast hosts many comforts not found in their arid native range, such as abundant fruits and small mammals, heavy cover and little competition for resources. In fact, these comforts allow coyote densities in the Southeast to exceed those in the West.


One of the largest coyote and deer studies in the Southeast was conducted on the Savannah River Site (SRS) in South Carolina by Dr. John Kilgo, a research biologist with the U.S. Forest Service Southern Research Station. Throughout the project, Dr. Kilgo and his crew radio-collared 60 fawns, within hours after birth, to determine mortality rates. What they discovered was eye-opening for hunters and biologists alike.

Of the radio-collared fawns, 73 percent (44 of 60) died, with coyotes being the most likely culprit in 80 percent (35 of 44) of those deaths. Bobcats were responsible for 10 percent (6 of 60). In an effort to make sure the act of placing the collars on the fawns didn’t affect their ability to escape predation, Dr. Kilgo’s group conducted another study which included an adjacent private property where no fawns were collared. Using trail cameras to observe the number of fawns per doe, they found no difference in fawn survival between the two locations.

More recently, Dr. Kilgo’s group investigated the effectiveness of a few commonly recommended management actions aimed at reducing coyote predation of fawns. A common theory suggested that enhancing fawning cover could potentially reduce the likelihood of predation by coyotes. Dr. Kilgo determined this wasn’t the case after finding no differences in predation between different levels of fawning cover, and that improving habitat may not reduce predation.

Another theory called “predator swamping” was adapted to apply to deer when adult sex ratios are balanced. This was first observed in herding plains game in Africa where predators are overwhelmed by the large number of newborn prey because they are all born in a short period of time. Predators can only eat so much at one time, so a higher percentage of prey survives. Balancing the sex ratio of a deer herd leads to a shorter, more intense rut and causes fawns to drop in a shorter period of time. Theoretically, if predator swamping could be applied to deer and coyotes, a higher percentage of fawns would survive.

To test this theory, Christopher Shaw (also with the U.S. Forest Service) and Dr. Kilgo compared fawn mortality rates between the low-density deer herd on SRS to a high-density deer herd on a nearby private property. Although coyote densities were similar on both areas, the rate of predation was the same. It appears that predator swamping is yet another theory that doesn’t work, at least on these study sites. Since Dr. Kilgo’s research began, several other studies across the Southeast sought to answer the many questions surrounding the interaction between deer and coyotes.

In northeast Alabama Cory VanGilder, a University of Georgia graduate student, under the direction of Drs. Karl Miller and Grant Woods, conducted a study attempting to increase fawn survival through predator removal. After monitoring the number of fawns per doe with trail cameras, the property was intensively trapped for predators, especially coyotes. On the 2,000-acre study site, 22 coyotes and 10 bobcats were removed.

Not surprisingly, the number of fawns per doe more than doubled the year following the trapping effort. Using a similar method Brent Howze, another UGA graduate student under the direction of Drs. Karl Miller and Robert Warren, conducted a study in southwest Georgia. This time two study areas were included: one heavily trapped for predators and one not trapped. Like the other studies, they found that fawn survival was more than double where predators were intensively trapped.


The studies previously described all seem to paint the coyote in a bad light, so how could this animal have any positive impacts? Some believe that coyotes have filled a critical niche in the ecosystem vacated by the nearly extinct red wolf and extirpated eastern cougar. We can’t deny that humans have changed the landscape forever, so does this niche really need to be filled, or have humans filled it as the No. 1 predator of deer? In hunted areas one could argue yes, but what about suburbia where hunting has declined or been eliminated?

Sarah Saalfeld, an Auburn University student under the direction of Dr. Stephen Ditchkoff, conducted a study to see if fawn survival was impacted by coyotes in a more developed setting. After examining mortality factors of fawns in an urban Alabama study site, they found that fawns suffered a 67 percent mortality rate with coyotes being the leading cause, contrary to the expectation that vehicle collisions would be highest source of mortality.

For areas overrun with deer, a coyote may be a welcome guest to some. But let’s not stop with deer; after all we do have to give this efficient predator some credit. Many suburbs are plagued with feral-cat problems. Domestic cats are well-documented enemies of songbirds, some of which are in severe decline. Because fawns are an available food source for just a short period of time, coyotes must have other resources for the rest of the year, and they just so happen to have a taste for cats. I personally believe this to be a far superior method of feral-cat control than the increasingly popular program of trap, neuter and release. Unfortunately, coyotes haven’t yet learned to tell the difference between feral cats and those with a collar, or the Chihuahua who dares to venture out after dark.

Where is the research headed now? These studies have provided a tremendous amount of information, but likely created an equal number of questions. So far, most of the studies were carried out in the ridge and valley and the upper coastal plain regions of southeastern states and areas with moderate to low density deer herds. In order to understand deer and coyote interactions throughout the piedmont region of Georgia, the largest region of the state, Georgia Department of Natural Resources (DNR) and the University of Georgia recently began a collaborative study on two piedmont Wildlife Management Areas (WMAs).

Under the direction of Dr. Karl Miller, graduate students Will Gulsby and James Kelly along with DNR biologists set out last fall to gather preliminary data assessing deer and coyote abundance. The primary goals of the project are to determine the level of fawn mortality related to coyotes on B.F. Grant and Cedar Creek WMAs, evaluate a new method of estimating coyote abundance and develop a large-scale habitat model to predict coyote abundance across a large landscape. The selection of the study sites will allow researchers to differentiate coyote impacts between traditional deer management and quality deer management.

Will Gulsby, a Ph.D. student, said, “This research is quintessential to understanding how the density of coyotes and the density of deer in a given area interact. Our ability to make critical deer-management decisions depends on our knowledge of how varying densities of both species can affect management goals.”

Another project at Fort Rucker in Alabama seeks to determine how the age and sex of fawns may affect their susceptibility to coyote predation. Angela Jackson, an Auburn University graduate student under the direction of Dr. Stephen Ditchkoff, has radio-collared six fawns to date, and only one has survived.

Dr. Ditchkoff said, “Most mortality is occurring after the fawns reach three weeks of age, which means they are mobile.”

This supports the evidence from the SRS studies that indicates fawning cover has little impact on the level of predation and further condemns the application of predator swamping to southeastern deer.

What have we learned from all this research? There is overwhelming evidence that coyotes can have an impact on deer populations, and the idea of coyotes being insignificant is obviously debunked. As for “Friend” or “Foe,” it really depends on your point of view and circumstances. Probably the more important question on a hunter’s mind is, “How does this affect the area I hunt?” The answer is, “It depends,” which is probably one of the most common phrases uttered by Dr. Karl Miller regarding wildlife management.

I can tell you this — if the deer population in your area is below carrying capacity, and you’re not satisfied with deer density, the first step is reducing your doe harvest.

Trapping coyotes is another more intensive option but can be expensive and must be done correctly to be effective. If you trap, it must be conducted immediately prior to and during the fawning season, or other coyotes will quickly repopulate the area. Opportunistic harvest of coyotes (i.e. shooting every one you see while deer hunting) will typically have little or no effect. In some cases it may even worsen the problem by temporarily reducing competition for resources, which can increase coyote pup survival.

Until we have more southeastern coyote/deer research under our belt, those are the management options we have to work with. Regardless of the methods you choose, I highly recommend consulting a wildlife biologist to help you efficiently meet your management goals. I’ve worked with numerous hunt clubs that believed that coyotes were decimating the local deer population only to find out that their harvest rates far exceeded what the herd could handle. Deer hunting and management are evolving rapidly, and relentless research is the only way to keep up. Contacting your local wildlife biologist is usually the best way to keep up with the most current management strategies.
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