Abstract
M.Sc.
In South Africa, there are no reliable statistics regarding animal numbers and distribution. The goal, therefore, of this research is to provide the framework and procedure for obtaining these statistics efficiently and accurately.
Available sampling methods and sampling frames were investigated and it was decided to carry out a sample survey because the Gauteng Province consists of a large number of holdings (land parcels). In the Gauteng Province, where a complete list of farmers or land owners is not available, it was decided to use an area sampling frame. Once the choice of sample design was made, the survey objectives were defined according to the clients’ needs.
The sampling frame was constructed using various land parcel layers. These land parcels were merged, using GIS software, into one continuous layer of land parcels. They were then stratified to reduce the variance of the variable (animals) under study over the entire area, using area of land parcel and land-cover. The sample size was then calculated and the land parcels were selected randomly for survey purposes.
The survey was conducted between September and December 1999 and the questionnaires were input into a database for the estimation procedures. The closed estimation procedure was used because it is the only possible option if the data surveyed are referenced to the land parcel (and not to a farm that includes several land parcels).
The area frame sampling methodology worked well for cattle, sheep, horses, pigs and dogs/cats and to a lesser extent for goats, donkeys and game. The area frame method did not work well for poultry (because of extremely high values in a few land parcels), ostriches or mules (these are rare in the province).
Spatial distributions and density distributions were then interpolated from the animal counts taken in the survey and they give a general idea of the location of animals. The distributions of cattle, sheep, horses, pigs and dogs/cats are reliable. The distributions of the rest are distorted due to extreme counts in a few land parcels but a general idea of concentrations can still be inferred.
Considering that no historical data exists and that the overall goal of this research was to get an idea of animal
numbers and the distribution of animals in Gauteng province, it can be considered successful, in that decision-
makers now have a reliable source of information from which good decisions can be made.