A Bird's Eye View of Deer Habitat QualityFriday, February 03, 2017
By Dr. Steve Demarais, Dr. Bronson K. Strickland, and Chad M. Dacus, Mississippi State University
Research shows that regional land-use trends influence deer
antler size, and habitat management on your hunting land will
produce more quality whitetails.
Download the full PDF here
Most QDM'ersare aware of the variation in body and antler size
of whitetails throughout their range in North America. On average,
deer harvested in Wisconsin are larger than those harvested from
Florida. This is largely due to genetics that code for larger
bodies in the colder, northern environments, and smaller bodies
that more efficiently thermoregulate in the warm environments of
the South. This genetic predisposition coupled with differences in
food quality and abundance generally explains why bigger deer are
associated with certain regions of North America. With this in
mind, it's no surprise that Iowa and Illinois consistently produce
some of the largest bucks each year.
But have you ever wondered why there is so much variation in
deer body and antler size within a geographic region? Like many
states in the Southeast, Mississippi has areas that are known for
relatively larger deer (for example the Delta region) and smaller
deer (the Lower Coastal Plain), but within these regions there can
be significant variation in the quality of deer produced. Why?
Could subtle, local variations among habitats affect physical
variation among deer? This information would be most helpful in
making practical habitat management decisions.
Beginning in 2000, deer biologists with the Mississippi
Department of Wildlife, Fisheries and Parks cooperated with the
Deer Ecology and Management Lab at Mississippi State University to
answer this question. We digitized the boundaries of more than 200
private properties and state wildlife management areas from across
Mississippi into a Geographical Information System (GIS) and looked
for underlying patterns in soil quality and habitat configuration.
We compared these land characteristics to the average antler size
of 2½-year old bucks harvested from each location. In addition,
because deer harvested in one area likely used vegetation outside
the property boundary, we added a 1/2 mile buffer around the
property boundary and included those habitat characteristics in our
We calculated average antler size (Boone & Crockett Score)
for bucks harvested on each property from 1991 to 1994 to coincide
with satellite imagery from that time period, yielding 203
populations for analysis. We used 2½-year old bucks for our
analysis because that age class provided the largest sample for
each property (this time period was prior to widespread application
of QDM buck harvest principles in Mississippi and the statewide
Next, for each property we gathered satellite imagery data that
characterized variation in deer habitat quality. These habitat
variables included percentage of the property in: agriculture,
fields, bottomland hardwoods, upland hardwoods, high-density pine
trees (i.e., pine plantations), low-density pine forest (like older
long-leaf pine forests), and clearcuts. Also, we looked at overall
habitat diversity. The resultant dataset contained the average
antler size of 2½-year old bucks and the percentage of each
vegetation class present on each property, yielding valuable
information about land-use characteristics that are most related to
Land-Use and Antler Size
Our results clearly demonstrated that in landscapes dominated by
dense forests, land-use types that promote the growth of forbs
(broadleaf plants browsed by deer) and associated groundcover plant
communities should positively influence deer habitat quality and
antler size (and likely body size and reproduction as well).
The percentage of a property in agriculture, or agriculture and
field, positively influenced antler size in some regions;
conversely, the percentage of a property in pine forest negatively
influenced antler size in some regions. The results varied somewhat
by region, but in all regions studied, properties with a greater
percentage of medium- and high-density pine forests tended to have
smaller antler size. The Lower Coastal Plain region in southern
Mississippi displayed some of the most striking relationships, with
a half-inch decline in population antler size with each 1 percent
increase in high-density pine forest.
So, for example, a property in that region with 20 percent more
closed-canopy, high-density pine forest than surrounding properties
would have a 10-inch smaller average antler size. Properties that
are dominated by closed-canopy pine forests simply do not provide
enough quality forage for deer. So what about hardwoods? Believe it
or not, the effect of high-density, closed canopy hardwoods had an
effect similar to that of pine forests. That is, if the forest is
so dense that light can't reach the forest floor, it doesn't matter
what type of trees are in the forest. Having an opencanopy forest
that promotes the growth of knee-high vegetation for deer food and
cover is what is imperative! Sure, acorn production is very
important and provides an energy boost during the fall and winter,
but what are these hardwood forests producing for deer the other
nine months of the year? An article in the February/March 2011
issue of Quality Whitetails by wildlife biologist Dave Edwards,
titled "Moving Mountains," makes the point well. After surveying a
predominately hardwood forest in Virginia, Dave concluded "the
mature hardwoods were wide open and park-like," and "the primary
limiting factors of the property were adequate, high-quality food
and cover for deer."
As you might expect, we found the opposite effect with
agriculture. As the percentage of the area in agriculture
increased, so did deer population antler size. There are three
points to consider statehere. First, row-crop agriculture provides
an abundant source of high-quality forage for deer (albeit much to
the aggravation of farmers), which can be replicated on a much
smaller scale with food plots. Second, there's a synergistic effect
in that areas with row-crop agriculture are also areas of higher
soil quality and fertility. This greater soil quality also produces
natural vegetation of greater nutrient content.
So deer in these agriculture-rich regions get the direct benefit
of forage from agriculture production and also higher-quality,
naturally occurring forage. Third, there are limitations to the
extent of agriculture that is beneficial. In areas dominated by
agriculture, the lack of cover needed for refuge can keep deer
population numbers down, so the addition of cover on these
properties can actually boost habitat quality and deer numbers.
Conclusions of the Study
On a statewide scale, our results demonstrated a mechanism for
the spatial variation observed in deer population antler size.
Within regions of similar soil nutrient quality, variation in
antler size was explained by land-use types that either promote or
suppress the growth of quality deer forages. For example,
agriculture is a land-use type that promotes quality forage, and
high-density pine or hardwood forest is not.
Please keep in mind that our results do not condemn pine and
hardwood forests altogether but emphasize the importance of
thinning, burning, and other practices that open forest canopies
and stimulate the production of deer forages.
Managing a forest for timber production and for wildlife can be
a tradeoff. If forest land makes up a small percentage of your
property, then maximizing timber value of the forest may not be
detrimental to deer habitat quality. However, if your property is
composed primarily of forest, then how the forest is managed will
have a significant impact on the deer forage production and overall
deer habitat quality.
A caveat we think worth mentioning is that suitable habitats
will encourage greater deer densities, which may negatively affect
antler size through increased competition for food. The
relationships we found between deer antler size and habitat type
among the 203 properties we studied do not account for deer density
relative to carrying capacity. Instead, the results we found were
apparent in spite of differences in deer density among the
properties. If we could have accounted for differences in deer
density we believe the relationships between habitat type and deer
antler size would have been even stronger.
What Does It All Mean?
Our results from a large-scale, state wide analysis provide
validation for what most deer biologists and experienced QDM'ers
already knew - habitats that provide abundant food will yield
higher-quality deer. Our findings show that land-use types which
promote and maintain forb-rich plant communities should positively
influence deer body and antler growth. Conversely, large expanses
of closed-canopy forest (pine or hardwood) will limit the
production of high-quality forages and may cause deer population
antler size to decline.
The replace- ment of row-crop agriculture with Conservation
Reserve Program pines is also likely to reduce habitat quality.
Managers of deer populations associated with closed-canopy forests
should increase the production of annual and perennial forbs by
thinning and use of prescribed burning. In pine plantations, the
use of selective herbicides to remove mid-story hardwoods in
combination with prescribed burning can also increase the
production of high-quality deer forages and improve deer habitat
quality. Furthermore, supplemental food plantings are an option for
hunting clubs that lease property and do not have the ability to
manage the forests they hunt. A system that produces abundant
year-round, high quality food plantings should improve diet quality
for deer populations in dense forests.
However, once ideal deer habitat is created, the gain can be
quickly lost if deer populations are not kept well below the
habitat's carrying capacity. Deer managers must maintain adequate
doe harvest and population levels so the habitat management will
continue to yield quality whitetails.