Transcript Wildlife Management - Midlands State University

Wildlife Management
Habitats
Questions
• Discuss the main aspects that should be considered
in planning a wildlife management programme.
• Critically evaluate the advantages and
disadvantages of intergrating wildlife production
with cattle production.
• Describe with NAMED examples the capture and
translocation of wild animals.
• Explain how predators and human disturbances
can be controlled in wildlife production.
• Discuss the implications of using fire as a
management tool in Zimbabwe.
Bush Control
Objectives of bush control are:
- To control bush encroachment
- Increases number and visibility of grazing animals
Bush Encroachment
• The invasion and/or thickening of aggressive undesired
woody species resulting in an imbalance of the grass:bush
ratio, a decrease in biodiversity, and a decrease in carrying
capacity
• In addition to browsing by domestic stock and game the
direct uses of woody plants in southern African savannas
include their use as firewood, rough construction timber, the
production of charcoal and woodcarvings.
• In areas where trees are used for timber, harvest rates
commonly exceed replacement rates.
• In other areas where woody plants are not subjected to
harvesting and where cattle and game ranching are practised
exclusively, an increase in woody plant abundance is
common.
Bush Encroachment
• This increase in woody plant abundance is
commonly referred to as "bush
encroachment" and involves the invasion of
grasslands and the thickening of savanna
• The causes of bush encroachment are
elaborated upon against the background of
two important models:
Bush Encroachment
• Walter’s Two-layer Model, which maintains
that, if the grass layer is overutilised, it loses its
competitive advantage and can no longer use
water and nutrients effectively. This results in a
higher water and nutrient infiltration rate into the
subsoil. Such a scenario will benefit trees and
bushes and allow them to dominate.
Bush Encroachment
• The State-and-Transition Model, which
recognises the dynamic nature of savanna
ecosystems. Savannas are event-driven where
rainfall and its variability plays a more important
role in vegetation growth (and composition) than
the intensity of grazing. It implies, therefore, that
bush encroachment is not a permanent
phenomenon and a savanna could be changed to
its grass-dominated state by favorable
management or environmental conditions.
Bush Encroachment
• The major factors determining the functioning and
dynamics of savannas are the following:
• PRIMARY DETERMINANTS, such as rainfall, soils and
nutrients, are functions of a specific geographical region
and are to a certain extent beyond the farmer’s control.
Rainfall, together with soil moisture balance, has an
overwhelming effect on vegetation structure, composition
and productivity.
• Rather than a gradual annual increase in bush numbers, the
general view is that woody plants establish in large numbers
during certain years, and at varying intervals.
• Prolonged denudation of soils caused by droughts and
grazing, followed by above-average rainfall years with
frequent rainfall events, favour mass tree recruitment.
Bush Encroachment
• SECONDARY DETERMINANTS: These act within the
constraints imposed by primary determinants.
• They can often be directly modified by management.
• The exclusion of occasional hot veld fires, the replacement
of most of the indigenous browsers and grazers by
livestock, injudicious stocking rates, poor rangeland
management practices, and artificial water points are
regarded as the major causes of bush encroachment.
• In the past, high-intensity fires played a major role in
maintaining open savannas. With the introduction of cattle
farming, veld fires were suppressed – and this is regarded as
a major factor contributing to bush encroachment. Although
fires kill tree seedlings and saplings, mature woody plants
are seldom killed and most coppicing species are able to
regenerate and grow actively.
Bush Encroachment
• Bush encroachment is the suppression of palatable grasses
and herbs by encroaching woody species often unpalatable
to domestic livestock.
• Therefore, bush encroachment reduces the carrying capacity
for livestock.
• Many people believe that either heavy grazing by domestic
livestock or fire is the sole cause of bush encroachment.
• Belief in grazing as the sole cause of bush encroachment
stems from Walter’s (1939) two-layer model.
• This model states that grasses typically outcompete trees in
open savannas by growing fast and intercepting moisture
from the upper soil layers, thereby preventing trees from
gaining access to precipitation in the lower soil layers where
their roots are mostly found.
Bush Encroachment
• When heavy grazing occurs, grasses are removed and soil
moisture then becomes available to the trees, allowing them
to recruit en masse.
• The fact that many bush-encroached areas are heavily
grazed means neither that grazing causes encroachment nor
that Walter’s modelis correct.
• Bush encroachment is widespread in areas where there is a
single soil layer and where grazing is infrequent and light.
• As a consequence of the inadequacy of previous
explanations for the occurrence of bush encroachment,
several new models have been put forward to explain
treegrass coexistence.
• One of the most widely-cited disturbance models of treegrass coexistence in savanna is that of Higgins et al. (2000).
Bush Encroachment
• Higgins et al. (2000) hypothesized that grass-tree
coexistence is driven by the limited opportunities for
tree seedlings to escape both drought and the flame
zone into the adult stage.
• Bush encroachment occurs due to increased tree
recruitment caused by reductions in grass standing
crop and hence fire intensity.
• They predict that rainfall-driven variation in
recruitment is more important in arid savannas,
where fires are less intense and more infrequent.
Bush Control
Method of Bush Clearing
1. Mechanical method
- This involves hand felling using axes, saws, muttocks,
chain saws, bull dozers and root ploughs.
2. Chemical Method
- use of arboricides or wood plant poisons.
3. Natural Method
-Browsing animals and fire, these seldom kills woody plants
but can slow their growth and spreading.
- A mixture of pure browsers such as Kudu, giraffes, black
rhinos with pure browsers can be used to control woody
plants.
Consequences of bush clearing
• Bush clearing with moderate grazing pressure will
reduce runoff and erosion.
• There is pronounced rise in moisture available to
other plants.
• Nutrient cycling is increased.
• There is increased yield and productivity of grasses.
• Grass species composition may change.
Main aspects to be considered when planning
and managing wildlife
1. Habitat Assessment
- consider the vegetation species present. The grass:shrub
and tree ratio should be determined.
- Areas can be defined into five categories in relation to
their use by wildlife namely:
(a) Broken hills and kopjes for refuge in early and mid season
grazing.
(b) Grass land and vleis – for early and late season grazing.
(c) Scrub savanna to woodland – this is a general year round
habitat.
(d) Thicket – for refuge, browsing and shade.
(e) Riverine – for late season browsing and grazing.
Main Aspects
2. Species
- Existing species will occupy and various habitats, and these
should be identified.
- Signs of spool, feeding and droppings will assist in
identification.
3. Fencing and grazing systems
- The suitability of fencing and grazing systems should be
examined.
- Select the most appropriate fence in relation to the species
to be contained and the composition i.e. wood fence, metal
wire fence
- Site the fence carefully enclosing suitable habitats of
browsers and grazers and include less productive areas such
as hills and steep valleys.
Main Aspects
4. Water
- distribution, availability and reliability of existing water
supplies should be ascertained.
- Artificial water sources should be undisturbed as some
species are shy but will drink from artificial ground supplies
or shallow depressions filled by overflow from troughs.
5. Human disturbance and Predation
- includes human presence, uncontrolled dogs, poaching
artificial barriers such as canals, roads, railway lines.
- Lack of planning when setting up fences, water points,
refuge areas might cause some other species to be disturbed
in one form or another.
- Control of human activity and elimination of dogs is
absolutely essential.
Main Aspects
- human habitation, cattle handling facilities and dip tanks
should not be included in suitable game areas.
- Natural predation is difficult to control and is probably of
benefit in that it eliminates weaker organisms from a species
so maintaining a healthy vigorous population and stability
of various habitats.
6 Population Density
- This must be carefully studied and recorded to avoid over
population.
- Over population by one species can at times be
demonstrated in the veld condition where selective grazing
result in replacement of palatable species by unpalatable
species.
Main Aspects
7. Resting of Grazing Areas
- It is necessary particularly after a fire.
- Animals will move to areas with grasses and water
thereby resting the areas.
8. Salt Licks
- These should be available freely to game.
- Used to control movement.
Main Aspects: Salt Licks
-A salt lick is a salt deposit that animals regularly lick. In an
ecosystem, salt/mineral licks sometimes occur naturally,
providing the sodium, calcium, iron, phosphorous and zinc
required for bone, muscle and other growth in wildlife.
Harsh weather exposes salty mineral deposits that draw
animals from miles away for a taste of needed nutrients.
-People use salt licks to attract or maintain wildlife, whether it
be for viewing, photography or hunting purposes. Many
companies now produce salt that includes all the trace
minerals and is fairly inexpensive. It comes in either bagged
or block form.
-The most common method for using bagged salt is as follows:
Main Aspects: Salt Licks
-Locate an area near a water source, food plot,
game trail or an old stump.
-Make sure the area is devoid of vegetation and
debris. Using a shovel, make a small
depression roughly 1.2 m to 1.8 m in diameter.
-Spread approximately 12.5 to 25 kgs of
salt/mineral mix on the ground and mix in a
small amount of the removed soil. The stump
location is ideal because it resembles a
naturally formed salt/mineral lick.
Main Aspects: Salt Licks
-For salt blocks, the usual method is to follow the first
two steps above, dig an 45cm to 50cm hole in the
middle, drop the block in and cover it with soil.
-After several good rains, the mineralized salt
dissolves into the surrounding soil. Wildlife find the
salt/mineral and begin licking and eating the soil. An
artificial salt lick usually lasts from 6 months - 1
year.
-Salt blocks are also used by farmers for domesticated
animals.
Habitat Manipulation
1. Burning Veld
- grasslands burning provide nutritious grazing in
spring.
- It is important when bush clearing or ring barking
has eliminated some of the trees.
2. Erection and Alignment of Fencing
- Use four strand wire of high strain steel wire.
- The bottom strand should be 360mm from the
ground level.
- Use plain wire so as not to damage hides.
- On boundary fences to contain animals on the farm
use 10-12 strands which is 1.5-1.18 m high.
Habitat Manipulation
- Fences should be clearly visible to game so as to avoid
collision which may cause injury or death.
- In thick bush it is advisable to clear a strip about 7m wide
on each side of the road these acts as roads or fireguards.
3. Permanent Water Sources
- These are essential for resident game species if cattle are
moved in a rotational grazing system, troughs must be kept
topped up with water for the remaining game.
- An artificial pool can be constructed and filled with sand to
avoid cattle falling in.
- The game can then dig for the water.
- Small weirs in sand rivers are also useful for game digging.