As I discussed in previous Deer & Deer Hunting articles, white-tailed deer populations seem to have peaked throughout much of North America and now are on the decline — in some areas sharply. Obviously, fewer deer means fewer hunting opportunities.
By John Ozoga
For Deer & Deer Hunting
The reasons for this deer population decline undoubtedly vary from one section of the country to next. This is a complex issue. Excessive deer mortality factors might occur for many reasons, including malnutrition, predation, disease, as well as other natural and human-induced factors. Regardless, the apparent primary reason for this population decline is high mortality among fawns and resultant poor annual deer recruitment.
It’s my contention that the primary problem is habitat related on Northern deer range, and is probably the case in the Midwest and Southwest, too.
In the North, poor quality deer wintering cover is the primary problem. A deficiency in optimal protective conifer cover and insufficient natural browse supply have contributed to increased mortality of wintering deer as well as newborn fawns. Poorly nourished deer not only suffer heavy loss due to starvation, they also are more vulnerable to predators, especially when restricted to poor quality shelter during periods of deep snow. Probably most importantly, however, especially following prolonged winters (as have occurred recently), poorly nourished pregnant does tend to produce inferior offspring that are more likely to die.
In the Southwest, periods of severe drought probably lead to similar consequences. Likewise, in the Midwest plains, changing farming practices have led to a decrease in the amount of high quality fawn-rearing habitat. Major changes include the recent conversion of tallgrass habitat to wheat production, resulting in less quality fawn-rearing habitat and increased fawn losses due to hypothermia and coyote predation.
When debating predation effects from a management standpoint, the problem is to determine if predation of fawns is the major cause of high deer mortality rates, or is it merely compensatory in nature. That is, if fawns are likely to die from other causes, such as disease or malnutrition, then predation is compensatory and fawn losses are inevitable.
In the Southeast, declining deer numbers can be directly linked to the recent spread of coyotes into that region and heavy losses of newborn fawns to predation. In other words, deer losses due to predation are additive and control or eradication of coyotes would presumably lead to an increase in annual deer recruitment rates and deer population increase – a number of studies have proven this. The question, of course, is coyote control wise or practical? Likewise, if not, then what are other management alternatives?
Largely under the direction of Georgia University professor Dr. Karl Miller, researchers launched a series of projects to address these concerns. I’m certain hunters will find these study findings interesting – but probably will not be elated with the conclusions and/ or recommendations.
Coyotes in the Southeast are not evenly distributed across the landscape. As elsewhere, they show preference for certain habitat types, such as agricultural areas, natural openings and early successional habitat, where preferred prey and certain seasonally available fruits and soft mast are most abundant – not dense mature forest cover.
Coyotes prefer some degree of habitat openness and tend to travel cover edges. Sound familiar? So do white- tailed deer. Although many factors influence coyote use of habitat and space, two primary patterns have been identified: some coyotes can be considered “residents,” while others are referred to as “transients.”
Resident coyotes are generally reproductive pairs that demonstrate attachment to a specific area. These preferred areas (i.e., territories) are relatively small compared to the extensive range traveled by transients.
In addition, resident coyotes tend to use certain vegetative patches within their home ranges very intensively. Since these heavily used areas are also favored deer fawning areas, newborn fawns within these patches of preferred cover likely suffer especially high death rates due to predation.
Transient coyotes roam over a much larger landscape and are less likely to concentrate their activities in any specific area. Hence, their predation of fawns should be more evenly distributed across the landscape.
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These differences relative to coyote social behavior, space use and fawn predation have been rather speculative in nature. However, John Hickman and others from the University of Georgia recently employed more sophisticated research techniques to quantify and evaluate how coyote behavior impacts newborn fawn survival rates and ultimately deer population recruitment. Hickman and his group investigated female coyote behavior and habitat in Georgia during the fawning season, when fawns are most vulnerable to predation. Their primary objective was “to document the possibility of differential coyote predation risk for fawns across the landscape and characterize habitat selection by female coyotes.”
The researchers tracked 15 female coyotes wearing high-tech GPS radio collars programmed to collect and store data on coyote locations (six to 36 times daily) during the fawning season in 2012 and 2013.
Compared to transient coyotes, resident female coyotes traveled smaller ranges (2.9 square miles versus 18.2 square miles) and revisited core areas of activity more frequently. This alone suggests that resident coyotes more thoroughly search relatively small areas within their established home ranges, likely leading to extremely high predation of fawns within those particular patches.
Clearly, this study demonstrated that resident coyotes tend to occupy the best habitat: that in early successional stages with greater prey abundance. In contrast, transient coyotes avoid encounters with residents by restricting their movements to areas between or on the margins of resident home ranges. Also, there is good reason to conclude that transient coyotes serve as “population founders.” That is, transients cover a relatively large area and learn select habitat sites occupied by resident coyotes. Once resident coyotes die, for whatever reason, including human- induced predator control efforts, transients quickly settle in those sites and repopulate the area.
As a result, unless coyote control can be conducted continuously over a large area, any removal efforts in choice coyote (and deer) habitat will likely yield only marginal and temporary results.
Another University of Georgia sponsored study, headed up by James Kelly, was designed to examine the seasonal food habitats of coyotes relative to habitat characteristics and associated prey abundance.
Logically, an abundance of alternative prey for coyotes during the fawning season might reduce their predation of newborn fawns – a testable hypothesis. If so, then habitat management geared to increasing alternative prey for coyotes would be an option if coyote control was deemed impractical. However, others suggest that such habitat management will only result in healthier and more productive coyotes.
The study reported by Kelly and his coworkers was conducted on two wild- life management areas in Central Georgia: the B. F. Grant area and the Cedar Creek area. Although the two areas were only about 5 miles apart, they differed in habitat traits, deer harvest regulations, deer density and presumably in abundance of alternative prey for coyotes.
Early successional habitat was more common on the Grant area (28 percent of area versus 7 percent on the Cedar Creek area). Therefore, it was assumed that small mammal densities were also greater there. Likewise, deer density was about twice as high on the Grant area as compared to the Cedar Creek area.
Based on the analysis of more than 350 coyote scats collected from the two areas, coyotes consumed a wide variety of vegetation during the late summer- fall period. During the rest of the year the coyote diet was dominated by animal prey.
During the fawning season (May- June), 61.5 percent of the coyote scats collected from the high deer density area (Grant) contained fawn remains, whereas only 13.3 percent contained remains of small mammals. In contrast, fewer coyote scats (26.7 percent) from the low deer density site (Cedar Creek) contained fawn remains, but somewhat more (26.7 percent) contained small mammals.
Hence, it appears when large numbers of fawns are available, that’s what coyotes will eat, regardless of smaller prey abundance, because it’s more energetically profitable to do so. That is, when fawns are readily avail- able, coyotes find them easily, being rewarded with a large amount of nutritious food for minimal energy spent searching.
Given these findings, Kelly and his group concluded that an abundance of alternative food items, such as small mammals, fruit and soft mast, will not serve to buffer coyote predation on fawns. Therefore, habitat management to increase availability of alternative food items for coyotes during the fawn- ing season probably will have minimal impact on coyote depredation of white- tailed fawns.
This is not to imply that habitat manipulation designed to improve newborn fawn hiding cover will not yield favorable results, especially in areas of limited dense ground level vegetation. The consequences of poor fawn-rearing habitat have been well documented, while the benefits associated with fawn-rearing habitat improvement have not.
One of the most recent studies conducted in South Carolina (Kilgo et al. 2014) failed to demonstrate any relationship between general habitat conditions and newborn fawn survival rates. The researchers involved in this particular study conclude the following: “Conceivably, the effect of vegetation on neonatal survival is manifested at a finer scale than we examined. Further research should focus on predator risk to finer scale vegetation conditions, such as those at neonatal bedsites.”
My studies, and others conducted in northern Minnesota, also show that healthy, maternally experienced does are more successful than younger mothers in rearing fawns when faced with predator risk. Presumably, these older does control better fawn-rearing habitat and more likely defend their fawns when threatened by predators – a relationship that has not been considered in Southeastern deer populations, where adult female deer are heavily exploited via liberal antlerless harvest.
Coyotes definitely impact deer populations in some parts of the country, but coyote control would be difficult, if not impossible in the long term.
Admittedly with some reservations, I still contend the following: If the management goal is to increase deer recruitment, then I believe the effort and cost involved in predator control would be better directed toward improving late winter/early spring nutrition for pregnant does and providing more and better hiding cover for newborn fawns.
Nonetheless, given the current problem relative to declining deer recruitment rates, certain changes in deer population management and deer harvest strategies might be required.
— John Ozoga has been D&DH’s top research contributor for more than 20 years. He is a retired deer research biologist.
— Hickman, J. E. et al. 2014. Coyote movements in Georgia: Implications for fawn predation. Journal of The Southeastern Association Fish & Wildlife Agencies (in press)
— Kelly, J. D. et al. 2014. Seasonal and spatial variations in diets of coyotes in Central Georgia. Journal of the Southeast- ern Association Fish & Wildlife Agencies (in press).
— Kilgo, J. C. et al. 2014. Coyote removal, understory cover, and survival of white-tailed deer neonates. Journal of Wildlife Manage- ment 78:1261-1271.
— Ozoga, J. J. 2012. How can we save more fawns: Predator control isn’t always the answer. Deer & Deer Hunting 36(1):15-20.
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