WILDLIFE MANAGEMENT- IMPALA
Management of impala on farmland in KwaZulu-Natal
A N Marchant

Impala were formerly distributed in the northern Cape, Transvaal and north-eastern KwaZulu-Natal (i.e. northern Zululand).
In KwaZulu-Natal they have been introduced extensively into thornveld areas outside their natural range and now occur as far south as Port Edward and as far west as the Spioenkop-Bergville area. The impala is a very useful farm game animal. It combines well with cattle and may even improve the productivity of a beef farm provided strict control is kept on the number of impala.
As far as is known impala do not pose any disease threat to livestock. Once established in an area it is normally contained by an ordinary stock fence provided the habitat is suitable, the area is large enough, and disturbance from stray dogs is kept to a minimum.

Harassment by dogs is probably the most important factor affecting wariness of impala and whether or not the impala remain on a property.
Habitat preferences

The impala is a thornveld animal requiring closed woodland and permanent water - it drinks daily and is rarely found further than 3km from water.
In KwaZulu-Natal, it is essentially a short grass grazer (like the sheep) but it does take browse (including pods) in winter, especially in the more "sourveld" areas. Fresh young grass growth is preferred to coarse or stemmy material, and the flush of grass following burning, grazing or mowing is particularly attractive to impala.

If a large number of impala are confined to a small area the palatable grasses will be eaten leaving the less palatable material of low nutritional value.
The ideal terrain for impala is flat to gently undulating thornveld. Provided the grassland is not dominated by unpalatable grasses such as ‘ngongoni’ (Aristida junciformis) and turpentine grass (Cymbopogon validus), the farmer may be reasonably confident of success with impala.

Social organisation
Impala are herd animals, which tend to remain in fixed areas. Each herd has its own home range, which will usually be vacated temporarily during severe droughts only. Three social categories can be recognized, viz.:

1.  Territorial males (often incorrectly thought to be ‘outcast males’ are mature, socially dominant animals in the prime of life. During the rut (April and May) they occupy a territory which they defend against all other adult impala males. 
2. Breeding herds comprise of all ages plus male lambs up to one year of age. The home range of a breeding herd may include a number of territorial males which each try to keep the females within their territories. 
3.  Bachelor herds are made up of sub-adult and adult males which are too immature physically, or too old, or of insufficient social standing to possess territories. 

These three categories are most evident during the rut. Much chasing of the bachelor males by the territorial males(s) takes place and the male lambs are evicted from the breeding herd. The territorial males attempt to retain their territories and the females. It is the strongest males that occupy a territory and this ensures that the best breeding material is used for fathering progeny. After the rut, the male lambs may temporarily rejoin the female herd.
Bachelor males entering the prime of life may either set up territories of their own during the rut if space permits, or otherwise displace aging territorial males.

Reproduction
Impala are seasonal breeders, mating in April and May, lambing during late November and early December. Normally impala females lamb for the first time at two years of age. However, there are rare cases where one-year-old females have lambed. Fertility rate is high - all mature females may be expected to lamb annually, except on marginal range, during drought, or when an area is overpopulated. Lambs are born in the approximate ratio of one male to one female.

Management
The camp for impala should be at least 100 ha in extent, and a minimum number of 10 animals (3 males and 7 females) are required to start a breeding nucleus.

As it is impracticable to drive impala from camp to camp it is essential that cattle (bulk grazers) be grazed in the impala area on a normal rotational basis. This will provide the impala with large areas of short grass thereby reducing the chances of site-selective overgrazing - a problem, which can be further, minimized by judicious use of fire. The four to eight camp cattle grazing and veld burning guidelines provided by the Department of Agriculture are suitable for farmers running cattle and impala, and the local agricultural extension officer should be contacted for more detailed advice on these guidelines.

Before any burning in sweetveld areas is carried out, written permission must be obtained from the local agricultural extension officer.

Where possible, mowing in mid and/or late summer is another very useful form of management providing the impala with short grass and encouraging rotational grazing.

One of the most important means of controlling overgrazing by impala is by strict limitation of their numbers. Impala should therefore be stocked at low to moderate densities. The maximum recommended stocking rate for impala in a cattle/impala enterprise is 1 impala per 4 ha. If impala are stocked at rates higher than 1 per 4 ha the following may occur:

Large areas become grazed down to grass root level.
Bare patches of soil and eventually erosion results.
Animals lose condition.
Lamb survival declines.
Lambing rates fall.
Social problems become exaggerated.
Parasite infestations increase.

In addition to the above, cattle production could also be adversely affected. To prevent overstocking, it is essential that surplus impala be taken off each year. The aim is to achieve a form of veld utilization where cattle and impala complement, rather than compete with each other.

Impala should be introduced only to areas where terrain favours counting and shooting or capture. Their numbers can increase prolifically and it is therefore necessary to count regularly and crop the surplus annually. In areas of dense impenetrable bush and steep terrain, it may not be possible to perform these two functions effectively and overpopulation and serious veld degradation can result.

Harvesting and sex ratios
Selective harvesting of impala can be achieved either by live capture and sale to other farmers, or by shooting.In the past, farmers and hunters shot the so-called "outcast" males in the belief that these were old, sterile and cantankerous individuals that were always chasing the other males away. As mentioned earlier these "outcast" males are the strong, virile, territorial males - the very backbone of the impala society.

Moreover, one ram was considered adequate for 20 or more ewes, since this was the case with sheep, so most males were shot. Such a heavy hunting pressure on males, especially territorial males, left the mating to the immature and feeble.

For maximum productivity, the farmers should control the composition of his impala herd as follows:

Do not shoot the territorial males, as they are the prime breeding stock for siring lambs.Maintain a bachelor herd for both mature and immature males.
Maintain a sex ratio of one male (including bachelor males) to two or three females (excluding lambs). Distorting the sex ratio beyond this will provide only marginal gains in production, but probably at the expense of the future genetic health of the population.

Harvesting should be done in early winter. This ensures that the remaining impala will have a greater supply of food to see them through the winter. Furthermore, the impala are likely to be in peak condition early in winter and so the carcasses will then be of the highest quality. The harvest should be concentrated on the bachelors, the immature and adult females, and any runts or deformed animals. Lambs may be included in the harvest but their removal will reduce production (kilograms of meat per year). However, this reduction in annual production will be marginal as long as the harvest does not exceed 25% of the female lambs and 50% of the male lambs.

Impala should be counted, aged and sexed prior to harvesting, preferably in March or early April (before the rut), so that the breeding performance of the animals can be assessed and the size and composition of the harvestable surplus can be calculated. The KwaZulu-Natal Nature Conservation Service can be contacted for advice on counting.

Female impala are distinguished from males by being hornless. Male lambs (i.e. less than one year) have short straight horns, yearling males (between one and two years old) have incomplete lyrate shape horns, and adult males (two years and older) have the fully lyrate horn shape

Legal status
Impala are classed as ordinary game in KwaZulu-Natal. The open season is 31 May to 31 August and an Ordinary Game License is required by a hunter, except if he is hunting on his own property when neither a license nor a permit is required. During the closed season, the hunter requires a Special Game License if not on his own property, or an Ordinary Game Permit (free) if hunting on his own property and to allow others to hunt on his property. Impala may only be hunted with a single action rifle firing a centre-fire cartridge with a calibre greater than 0.22.

KEY POINTS
Terrain should be flat to gently undulating.
Camp size minimum of 100ha.
If terrain unsuitable and/or camp too small, problems related to over-population with arise.
Maximum stocking rate should be 1 impala to 4 ha.
Graze, burn and mow the impala area on a normal rotational basis.
Remove surplus animals annually.
Maintain a sex ratio of one male to two or three females.