Ecology and management of white-tailed deer in - Florida Fish and ...

considered essential and the most economically practical method of sound management for
white-tailed deer.
Elements of Population Dynamics
Successful management of a deer herd requires a basic understanding of the factors
that influence population changes. Deer populations are constantly changing as new
individuals replace older animals. The elements of population dynamics include
reproduction, mortality, immigration, and emigration. Although obtaining accurate
reproductive and mortality rates (particularly mortality due to natural causes) can be
difficult, managers can use a variety of techniques to detect changes in the size and health
of the population. Estimates of population size, sex ratio, and age distribution are
population descriptors that provide valuable information for managers.
Population Growth Curve
The graphical display of a
typical growth pattern for a deer
population is a logistic or S-shaped
growth curve. Although actual
populations are unlikely to follow
the curve exactly, it illustrates the
general principles of population
growth and can provide guidance
for population management. The
initial, small population grows
relatively slowly because there are
fewer individuals reproducing. As the
population increases, there are more
Population
Density
22
K
Time
Maximum
Sustained
Yield
Logistic growth curve for a density-dependent population.
reproductive individuals, and the population grows more rapidly. The maximum rate of
population growth occurs at the midpoint of the curve, at a point referred to as the
maximum sustained yield. However, the increased numbers of individuals, all of which
require food and space, contribute to a decline in habitat quantity and quality. Eventually,
if allowed to progress, the rate of population growth falls to zero, as there is only enough
forage for an animal to replace itself. The maximum number of individuals that a particular
habitat can adequately support is called the environmental or biological carrying capacity
denoted by K in the above graph. If a deer population increases beyond carrying capacity,
the environment can no longer sustain the population, the habitat degrades, herd health
declines, and the population suffers. In other words, the deer herd is overpopulated. The
carrying capacity is extremely difficult to estimate and it varies from area to area according
to soil type and fertility, climatic conditions, and other factors that determine the quality
and quantity of food. Even within a given area, carrying capacity can vary from one year to
the next depending on weather conditions and the resultant food production.