International attitudes to biodiversity since 2002 have
presented a dilemma to the Game Industry as well as to the State and Provincial
Governments in South Africa.
There are many arguments, all with their own merits, for both the game
conservation sector as well as for the game business sector. Some species were
found permanently in some parts or regions of the province, others migrated
through sporadically, and others occurred peripherally on the borders of this
It is important to note that habitats and flora have
changed significantly since the 1700’s. Therefore the suitability of certain areas
for different species has also changed markedly. Areas which once were unsuitable for certain
species, are now suitable, and vice versa. Whether a certain species will
flourish on a certain farm, or not, cannot be determined merely by the fact
that it occurred in that area in the 1700’s. Therefore it is necessary that you
do research and determine what the specific ecological and sociological needs
of a specific animal are before you decide whether or not to include it in a
game management system.
Breeding And Population Growth
There is a
natural order of social
dominance hierarchy between the members of a population of animals, as well as
direct competition between members of the same gender (particularly noticeable
between males). Because of this competition, few (less than 20%) animals will
begin to reproduce when they reach sexual maturity. Socially dominant
individuals will prevent sub adult sexually mature individuals from mating.
With intensive production, where small breeding groups are kept separately in
enclosures, male competition is eliminated and sub adult sexually mature
individuals will likely breed successfully. Where animals are kept in extensive
natural conditions, most animals will need to achieve social adulthood before
they will breed. In other words, when the animal has achieved the
physical strength and size which will enable it to compete successfully in the
hierarchy, it may begin to breed.
population growth is not merely a measure of the rate of reproduction
of female animals. An actively managed
population of 100 kudu consists of 20 adult bulls, 40 adult cows, 20 first year
heifers and 20 second year heifers. The 40 cows produce 38 calves, in other
words, an increase of 95%.
Of these calves, 12 die before they are weaned, and 4 adults die of natural
causes. The population now consists of 96 adult kudus plus 26 calves, giving
124 animals in total as opposed to 100 before breeding. The population growth is therefore 24%.
Most calves and
lambs are born in a male/female ratio of close to 1:1. In nature, there is a
tendency for young adult males to move out of the population and the ratio of
female adult animals therefore increases slightly. The structure of a
population of adult, breeding-ready (socially mature)
animals can be slightly adjusted by management, in extensive conditions, to
increase population growth and so optimize production. Under
intensive production, with breeding animals separated into breeding enclosures,
the application of agricultural animal production
principles and techniques can further enhance the gender ratio
in favour of female animals (specialized expertise and advice must be sought
Establishing new populations
The gender ratio
of adult animals in a population becomes very important when a new species is
introduced or established. This ratio needs to take into account the desired
male/female ratio, and must also account for individual social competition.
With several strictly territorial species eg white rhinoceros, blesbok, water
buck, sable antelope, gems buck, reedbuck, and tsessebe, there needs
to be a minimum of three adult males in new populations or herd. If there were
only 2 males, the more dominant stronger male would continuously chase the
weaker animal until it would die of starvation or exhaustion, or suffer a
severe injury. If there were only one adult male in the population it would be
supremely dominant and kill all male offspring, or injure them as soon as
youths would attain sexual maturity.
growth is generally slow (about 25%), and therefore the establishment of too
small new groups of a species will mostly be uneconomical. Before one
decides on the number of animals required to establish a species, one needs to
study the age of social maturity/first mating, as well as the
expected population growth, and to take it into account when doing
the required financial planning.
Animal load and
carrying capacity remain the most important, and at the same time, the most
ill-understood and difficult to interpret factor involved in game management.
Other than in agricultural adult animal or
large stock unit (LSU), the game capacity cannot be estimated
by animal LSU carrying
capacity alone. There are five
components involved in calculating animal capacity in game farming:
The hectare size of the area suitable for the
species in question needs to be determined. This is usually only a fraction of
the total size of the available area or farm.
The overall suitability of this allocated habitat needs to be estimated
on a percentage basis (1-100%). The hectare size needs to be multiplied by this
percentage (of suitability for the species in question) to determine the total
amount of hectares available for the species.
there enough space (in hectares) to supply the needs of the particular species
for territorial and home-range needs in the confines of the farm,
habitat or enclosure? If not, the species may survive, but will not achieve its
potential population growth. This is usually more of a limiting factor for the game stocking capacity of an area than
the food supply capacity. What is the social herd/family size of the
species and how much overlap of territorial area is tolerated between neighbouring herds/families? This will give an
indication of how many animals can be kept in a specific area, if enough food
Stock Unit – Browsing Unit:
animal species has its own large stock unit (LSU) equivalent and browsing unit
(BU) equivalent. One LSU = one
head of cattle with mass of 450 kg with a metabolic energy intake of 500 kJ per
day. One BU = one non-lactating Kudu of 160kg.
Every animal species eats a
proportion of grass and non-woody plant material and a percentage of woody
plant material. The LSU and BU of a particular species of game needs
to be multiplied by the % intake of the respective plant materials in the diet,
mentioned above. These calculated answers must be multiplied for the planned
total animals of each species, and the totals of all the species on the farm or
enclosure need to be added together.
The LSU and BU carrying
capacity of the vegetation of each habitat unit on the farm needs to be
calculated separately. The LSU and BU of the total animal load should not
exceed the calculated total LSU and BU carrying capacity of all the habitats
added together. Please note that the food
supply carrying capacity has a direct relationship to the
rainfall of the current season as well as the long term rainfall. That is why
the carrying capacity and game load will vary over time. Table 8 provides
recommended game loads for specific rain fall limits within which an animal
species may prosper over time. Outside of these limits, game loads will be
In most instances it will be noted that a
much smaller game biomass than cattle biomass may be kept successfully on the
same farm. This is due to the societal special needs as well as the diverse
feed needs of game species, which are usually more limiting than the feed
carrying capacity of an area. Many farmers have the perception of “My farm can carry so many LSU cattle and
therefore should be able to carry the same amount of LSU for game.” This perception is false and is not at
all applicable to management of game!
Suitability of Habitat
A particular habitat, landscape or area
cannot be assumed to be suitable to a game species merely because it naturally
occurred there in the past. One has to consider the current condition of the
habitat and determine to what extent it fulfills the requirements of the
particular species. I mentioned earlier that vegetation and climate are
dynamic, and over time many temporary or permanent changes occur. Few habitats
are the same today as they were a few hundred years ago. The two main factors
driving these changes are man and his artificial technological development, and
the natural process of global warming.
The main parameters determining
suitability of habitat for a particular species include: temperature
(variations and limits), rainfall, topography, composition of vegetation
species, vegetation structure (grass height, tree and shrub crown height and
density), veldt type (sweet, sour, or mixed), nutritional value (nutrient
content) of plant material, taste (phenophase and growth stage) of plant
material, superficial sources of water, total available space (in hectares),
and infrastructure (human disturbance).