The methods for and the problems of recognizing bird and rodent damage are described. For birds the methodology for assessing the damage, and the necessary statistics for determining sample design and sample size exist. Damage is measured either by visual estimation of the percentage loss (sorghum, maize, millet) or by weighing/comparing of damaged/undamaged spikes/panicles (wheat/rice). Sampling usually involves randomly selected transects. A system is also available for assessing bird damage over large areas of District, Regional or even countrywide levels involving aerial surveys of crop hectarage and ground teams sampling damage levels at randomly selected points.

For rodents, the methodology is less well established but damage in the field is usually quantified in terms of the percentage of rows of cereals destroyed at germination (maize) or by the number of cut stems compared to uncut stems in sample quadrats (wheat, barley).

Manpower and resources for bird control do not often extend beyond control operation to damage assessments. As a result the necessity for and success of bird control has to be evaluated in terms of diminishing farmer complaints or expressions of farmer gratitude rather than objectively in terms of crop saved or cost-effectiveness. It is suggested that in the long run, emphasis must inevitably switch to damage assessments as the economic pressures on Africa continue to increase.