White-tailed Deer Food Habits and Preferences in the Cross Timbers

high and low fences, different livestock densities
and grazing systems, excellent to poor
range conditions, different classes of livestock,
presence or absence of agricultural forage
crops and supplemental feeding programs and
different densities of white-tailed deer. This
study differed from many previous works
describing deer foods in that data was
collected over such a broad geographic area
and wide variation of land uses.
Deer diets and available food sources were
studied from Spring 1996 to Winter 1998. Deer
diets were described by examining rumens
(stomachs) from deer collected on each ranch.
Available sources of food were described by
conducting vegetation surveys. Study ranches
were visited during May, August, November
and February to represent spring, summer, fall
and winter seasonal components of deer diets.
Drought conditions prevailed during much
of 1996 but rainfall increased during 1997.
Consequently, plant growth and relative
availability of food resources differed between
years and between sites during the study. This
situation may have confounded attempts to
describe the average deer diet in the Cross
Timbers and Prairies Region. However
“average” rainfall years in this part of Texas are
relatively rare, actually allowing comparison of
diet composition between wet and dry years.
Available food resources were estimated by
conducting vegetation surveys on each site
during the spring, summer, fall and winter. A
plant list was developed of all plant species
identified on study sites (Appendix A). An
availability factor was developed for each
species based on the results of the vegetation
surveys. A food resource’s availability factor in
simple terms describes how often a species
was identified during vegetation surveys for
each season.
A minimum of 5 white-tailed deer, primarily
does, were collected during feeding hours
following sundown on each site for two years
during May, August, November and February
(238 total deer). A sample of rumen contents
for each deer was collected and washed
through a graded series of sieves and stored
in 10% formaldehyde. Plant fragments were
studied and identified to genus or species
where possible by general leaf shape and
other external characteristics. Identification of
fragments was based on a plant reference slide
collection prepared at the beginning of the
study for each site. Identification of browse
(tender growth and leaves of woody plants)
and forbs (broad-leafed weeds) was based on
epidermal and morphological characteristics of
leaves and stems. Monocots (grasses or grasslike
plants) were identified by the size, shape,
absence or presence of hairs and specialized
epidermal cells.
Food items were identified to the lowest taxonomic
category possible, usually to at least
forage class (browse, grass, forbs, mast, agricultural
forage crop or commercial feed).
Remaining fragments were categorized to a
nonspecific forage class labeled “unidentified”.
Fragments that could not be identified to any
forage class were labeled “unidentified plant
material”. A photographic guide of woody
plants, forbs and grasses found in deer rumens
during the study is provided in Appendix B.
Seasonal preference ratings were developed
for each plant species identified in rumens.
In common terms, the preference value
(preference) refers to the degree a deer will
actively seek out a food item when other
possible foods are available, in other words,
what the deer likes to eat. The importance
value (importance) quantifies the volume of a
particular plant species in the deer diet. Plants
with a high importance value make up a
higher percentage of the seasonal or annual
diet. An analogy often used to explain this
concept is the relationship between sirloin
steak and hamburger. Many people would
prefer to eat sirloin steak, but hamburger meat
is often more important because it makes up
more of the total diet.
WHITE-TAILED DEER FOOD HABITS
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