The Impact of Predators on Deer in the Southeast

December 2016 WSFNR-16-51 The Impact of Predators on Deer in the Southeast David A. Osborn and Mark D. McConnell In the Southeast, white-tailed deer have multiple predators and individuals sometimes are killed by those predators. However, healthy deer herds can and do coexist in places with abundant predators. Although it is easy to dismiss the role of predators as purely negative when regarding deer management, it is important to remember that predators are a natural and normal part of a healthy, well-managed ecosystem. To assume predators have no beneficial purpose in deer management is to ignore the facts. However, when predator populations become too abundant and affect our deer management goals, an open discussion regarding the appropriate management action is justified. Predator reductions via trapping/shooting, habitat management, and/or changes in deer harvest are all possible options that require careful and calculated review of available facts. The answer is not a landscape without predators. That approach has led to drastic overabundance of deer populations that degrade habitat for many wildlife species. In this document we will discuss the current state of knowledge (i.e. scientific evidence) about predators as related to white-tailed deer in the Southeast, what management options are available, and the effectiveness of those options. DEFINING WHITETAIL PREDATORS In general, deer predators are fox-sized, or larger, mam- mals and sometimes even the American Alligator. Foxes rarely prey on deer but sometimes kill fawns when larger dog-related predators (wolves and coyotes) are missing. Deer Predators Feral pigs are opportunistic feeders which might occasion- The primary deer predators in the Southeast are typically ally prey on fawns, but research has not shown them to be coyotes, bobcats, and black bears with the exception of cou- important predators of deer. In the very limited areas gars and red wolves where they exist. Other predators such as foxes, feral pigs, domestic dogs and alligators kill deer where they are found in the Southeast, red wolves and infrequently and do not pose a serious threat to deer popula- cougars are deer-hunting specialists. In the absence of tions. larger cats and coyotes, bobcats can be the main predator of fawns and sometimes adult deer. Domestic dogs sometimes kill deer but probably have little effect on deer numbers. Although reported in the northern United States 43, it is rare for black bears to kill adult white-tailed deer. How- ever, since first reported in 1982 35, black bears are known to be important predators of fawns in some locations. Across the Southeast, coyotes are a major predator of deer. It was once believed coyotes killed only fawns and old or sick adult deer. Evidence now suggests that coyotes sometimes prey on all segments of the deer herd. Howev- er, recent research has shown they likely take few adult deer 26. Photo: Shane Roberts How Researchers Monitor Predators The most obvious signs that deer predators exist on a property likely are foot prints (i.e., tracks) and scat (feces). Learning to identify tracks and scat is the first step to predator identification. Wildlife biologists use man-made track stations to inventory predators. In addition, they collect scat to determine predator diets and sometimes to collect DNA samples. From these DNA samples they can identify predator species and sometimes even individual bobcats, coyotes or other predators 17. Individual identification is important when researchers try to estimate the total number of pred- Photo: Will Gulsby ators at a location and when they study an individual’s distribution across the land- Researchers prepare a predator track station by creating a 3-feet diameter scape. circle of hydrated lime and placing an attractant in the center of the circle. Unpaved roadways frequently are traveled by predators and provide a good location to search for tracks and scat. Predator tracks can be identified based on shape, size and relative placement. For example, members of the dog family all make tracks showing four toes and the toe nail marks usually are visible. Cat tracks typically are more round than dog tracks but also show four toes with the toe nail marks missing. Scat identification can be difficult when diets of the predator species are similar. However, cats have a habit of covering their scat by scratching together mud and debris. Members of the dog family might scratch near scat but they don’t make an effort to cover it. Bear scat changes in shape, size and con- sistency depending on seasonal changes in diet. In addition to tracks and scat, it is possible to make other direct and indirect observations of predators. Where coyotes exist, their high-pitched barking and howling at night is a sure sign of their presence. Re- Adapted from Pocket Guide to Florida Animal searchers sometimes perform howling surveys to monitor coyote abundance. Although elusive, predators occasionally can be seen while driving through a property, from a deer stand, or from trail camera pho- tos. However, these observations tell researchers lit- Researchers most often use track and scat surveys to monitor tle about predator abundance. The detection of pred- predator abundance. For coyotes they sometimes also use howl- ators on a property does not necessarily mean they ing surveys. are having a large negative effect on the deer herd. In fact, under certain circumstances predators might be helping to better manage the property’s deer herd. Deer Carcasses Finding a dead deer that has been fed up- on doesn’t necessarily mean it was killed by a predator. In fact, predators frequently feed on deer that died from other causes. In addition, a deer killed by one predator might be fed on by another. There- fore, researchers must be careful to not rush to judgement when they find a suspi- cious deer carcass. When they need to make an educated guess regarding which predator killed a deer, they use a system- atic approach. They first examine the kill site for detectable patterns that might help Photo: Daniel Crawford identify the predator. For example, was Researchers measure the distance between tooth puncture wounds to help de- the carcass dragged or carried to secluded termine which predator killed this deer. cover and fed on without much scattering of remains? If so, a cat or black bear 46 might be involved . Alternatively, if coyotes were For herds with typical production of fawns, removal involved, remains likely would have been scattered of some fawns by predators can help prevent exces- 46 over a much larger area . Did the predator leave be- sive herd growth when the harvest of adult females is hind its tracks, scat, or hair? Researchers often skin too low. However, when predators kill too many the carcass and examine it for puncture wounds and fawns or when predator-related mortality is combined other tissue damage. Predators sometimes can be dis- with excessive hunter harvest of adult females it can tinguished by the location and other characteristics of lead to localized declines in deer numbers. bite and claw marks. For example, when fawns are killed by coyotes they typically have bite marks on their head and/or neck with occasional bite marks on The only way to know if a property has a predator their backs, or elsewhere 47. Sometimes, when fawns problem is to monitor characteristics of the deer herd are killed by coyotes, the only evidence is blood, a over time. Researchers use trail cameras and hunter few tufts of hair and crumbs of flesh, bone, or fat 47. observations to estimate the number of bucks, does Bobcats also bite the head, neck or throat but are more and fawns. Of particular importance is the fawn re- likely to leave claw marks on the back, sides and cruitment rate (number of fawns surviving to 6 shoulders 39. In addition, bobcats often cover the car- months of age per adult doe). Just because a proper- cass remains with live or dead vegetation 28. When ty has deer predators it doesn’t necessarily mean it black bears kill fawns, bone fragments might be the has low fawn recruitment. only remains left at the feeding site 32. Domestic dogs typically feed very little on the carcass and they hap- hazardly bite the deer to kill it. Monitoring changes in a deer herd requires a degree of quality control. For example, trail camera surveys must follow a strict protocol to prevent erroneous con- clusions 19. Common mistakes are a lack of consisten- Changes in the Deer Herd cy in the timing of cameras being deployed from year Landowners and hunters should avoid jumping to the to year, failure to maintain adequate bait (corn) at conclusion that they have a predator problem just be- camera sites, and different numbers of cameras being cause there are predators on their property. Remem- used each year. These unintentional mistakes could ber, some amount of predation is normal for all wild- lead to a misunderstanding about the state of a deer life. In addition, deer die from other natural causes herd. Generally speaking, 1 camera per 100 acres for even when predators don’t exist. From a deer man- 14 consecutive days will provide the best estimate of agement standpoint, losing a few deer to predators population characteristics 19. doesn’t have much noticeable effect on a deer herd. that when more fruit occurred in coyote scat, the chance of finding deer fawns in the same scat de- creased. Therefore, the more fruit coyotes ate, the less deer fawns they ate 8. This does not necessarily suggest that managing for rodents, fruits and other alternative coyote foods will result in reducing coyote predation on fawns.

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