Buckmasters Magazine

The Deer Doctors

The Deer Doctors

By Bob Humphrey

New studies examine predator impact, protein effect and more.

Wildlife biologists, many of whom are hunters, spend a considerable amount of time in the field and come up with some pretty interesting stuff. Most of what we know about deer anatomy, physiology, biology, breeding behavior, food preferences, vocalizations and habitat use originated from a biologist before it was passed along to the masses by the club elders or the latest TV hunting expert.

Granted, some of the research seems a bit esoteric. After all, do we need to know seasonal variations in the average defecation rate of white-tailed deer, or the number of pellets per pile?

Even such studies can mean quite a bit to hunters, however. Because it’s impossible to conduct a truly accurate population census, and because it can be quite expensive and labor intensive just to get a good idea how many deer you have, you can count deer poop pretty cheaply and use the results to derive a rough population estimate that will suffice for many management applications.

That’s an extreme example, however, and most of the research conducted by professional wildlife biologists is not only useful, it also has direct or indirect application to both managers and hunters.

Just like hunters, biologists enjoy getting together to swap stories and compare notes. They do so throughout the year, but some of the brightest and best gather annually at the Southeast Deer Study Group meeting. This year’s assembly took place in Charleston, S.C., and what follows are some of the highlights.

PREDATORS

The rapid expansion of coyotes throughout the Southeast is a relatively recent phenomenon and we at Buckmasters have tried to keep you up to date.

Much of the information we’ve provided came from cooperative studies involving state and federal agencies and university researchers, as biologists continue to examine potential influences of coyotes on deer populations, particularly in regard to predation rates on fawns.

Because eastern coyotes are still relatively new to the equation, we don’t know a lot about their behavior. A wide body of literature exists about Midwestern and Western coyotes, and it’s tempting to apply that knowledge to the Southeast. However, recent research suggests eastern coyotes differ significantly from their western cousins in terms of behavior and movement tendencies.

This means more investigation is needed, and researchers from the University of Georgia (UG) say we need a coordinated information gathering effort among stakeholders throughout the region.

A prime example is a cooperative study between UG and the Georgia Department of Natural Resources (GDNR) looking at how coyote diet might shift in relation to deer abundance.

Similarly, a Virginia Tech study in western Virginia will look at whether the availability of alternative prey might have a buffering effect on coyote predation.

Another cooperative study between UG, GDNR and the Florida Fish and Wildlife Conservation Commission is looking at the effectiveness of coyote removal programs in increasing fawn recruitment.

You would assume that removing coyotes would reduce predation and allow more fawns to reach adulthood. Preliminary results suggest that might not be the case. Researchers advise managers to closely monitor fawn recruitment and realize that costly management actions like predator removal might not produce the intended or expected positive results.

More research is needed on the subject, and it won’t be easy convincing deer hunters that predator removal efforts could actually backfire. Then again, it wasn’t so long ago that we overcame widespread reluctance to shoot does. Hunters come around when presented with concrete scientific evidence.

HABITAT

Just as good food plots come down to good soil, healthy deer herds need healthy habitat.

In fact, the interaction between deer and their habitat is one, if not the most important, area of concentration for deer researchers.

Researchers from UG and the Louisiana Department of Wildlife and Fisheries are looking at variations in nutritional carrying capacity for different habitats.

Like many states, Louisiana has a diverse array of habitat types that vary in nutritional quality across different regions. Being able to estimate nutritional carrying capacity for primary habitat types could provide land managers with a useful tool to assess potential habitat quality, then decide how many deer the land can support.

Field work consisted of collecting plant samples representing consumable plant forage. Researchers then developed a model that will predict the number of days the habitat can support deer foraging for each habitat type.

Using feeding and diet quality data from other studies, the researchers can then rate the ability of each habitat type to support a sustainable deer population.

While we tend to think of habitat strictly along nutrition lines, the Caesar Kleberg Wildlife Research Institute (CKWRI) is looking at characteristics of fawn birth and bed sites on the Comanche Ranch in Texas.

If predator eradication isn’t as effective as we would like, we’re going to need other means to increase the number of fawns that reach adulthood (recruitment). Enhancing fawning habitat is one alternative.

The researchers evaluated bed-site habitat characteristics of newborn fawns, as well as fawns seven and 14 days of age. According to their results, fawns seem to select areas with high cover near a shrub. This certainly makes them less conspicuous to predators and might protect them from hot temperatures common in South Texas.

Maybe a similar study by UG and the Joseph W. Jones Ecological Research Center done in a longleaf pine ecosystem is more applicable to your situation. While much has been done in the Midwest, this was only the second such investigation in the Southeast.

Researchers measured micro-habitat variables at bed sites and compared them to random sites within individual fawn home ranges.

By applying statistical analysis, they found a positive relationship between bed sites and tree diameter, canopy closure, vertical height of vegetation and percent of cover up to 3.3 feet. Managers will use these results when making habitat management recommendations to increase fawn recruitment.

BEHAVIOR

All of the this is pretty neat stuff. If nothing else, those studies should give managers new tools to allow a given parcel of land to support as many deer as it should. But, let’s face it, most of us are looking for a little more direct application — something we can take directly to the field to be more successful.

Fear not, for the deer doctors have something to offer there as well.

A group of University of Tennessee researchers used GPS collars to monitor movement of bucks and does during the breeding season. It was not surprising they found overall movement rates increased more for bucks than for does, with the greatest increase occurring during peak breeding period.

Additionally, core area use dropped for bucks during peak rut, while it remained relatively constant for does. This suggests bucks are doing most of the traveling, although the researchers observed more excursions (long treks outside their home range) by does than bucks during the rut.

Conventional wisdom tells us older, more dominant males are more successful breeders. However, recent research has shown that younger, smaller, sub-dominant bucks also breed, and to a greater extent than was once thought.

Auburn University researchers set out to examine factors that influenced reproduction and found that antler size, antler characteristics and body size were all associated with male breeding success. In fact, certain body measurements were better predictors than others.

They also found that age alone was less of a factor when there were more older deer present. In other words, when more mature bucks are present, body characteristics are even more important in determining breeding success.

These findings could be particularly important where managers might be trying to increase reproduction or improve age structure in a particular population.

In keeping with a similar theme, researchers from Auburn University, Texas A&M University, Norfolk Southern Railway and the South Carolina Department of Natural Resources have been looking at whether or not yearling bucks use a different breeding strategy in populations with mature males present.

They found that yearling bucks concentrated movement within smaller areas than adult males. As a result, the biologists hypothesized that yearlings might remain in close contact with female groups and employ a sneaky strategy to breed. Instead of roaming the countryside in a frantic search for hot does, they simply hang out near the local does and wait for one to be ready to breed. This creates a bit of a quandary to the “let them go so they can grow philosophy.”

Also from Auburn is a study on reproductive success in relation to herd demographics.

Hunters might not care about the microsatellite DNA analysis or statistical hypothesis tests used to derive results, but most would want to know that average conception dates occurred a week sooner when more mature bucks were present. The presence of mature bucks resulted in fewer late-born fawns and a shorter, more intense rut (a compression of gestation dates, to put it in the researchers’ terms).

MISCELLANEOUS

The Southeast meeting also had its share of studies that included things like antler growth patterns, fire prescriptions, the captive whitetail industry, nutritional supplements and dog hunting.

Of particular interest to hunters, CKWRI and Comanche Ranch researchers found mean antler size of mature bucks in enclosures with pelleted feed was approximately 18 inches greater than for bucks in enclosures with only natural forage.

That tells us there’s a good chance supplemental nutrition might boost antler score on your lease.

They also found antler size decreased during drought, even with pelleted feed, which emphasizes the importance of maintaining quality natural forage even where supplements are used.

This is but a sampling of the dozens of research projects conducted around the country each year. The results provide managers with more accurate and effective ways to manage deer populations within their environment. They also give hunters greater insight into what makes whitetails tick so we, too, can be more successful.

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This article was published in the September 2013 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.

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Copyright 2020 by Buckmasters, Ltd