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 tree-grass 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 • 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 • 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: • Broken hills and kopjes for refuge in early and mid season grazing. • Grass land and vleis – for early and late season grazing. • Scrub savanna to woodland – this is a general year round habitat. • Thicket – for refuge, browsing and shade. • 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 • 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.