Abstract :
Copsychus malabaricus is a popular chirping bird because it has a melodious voice and distinctive style, and is one of the birds that has high economic value. The limited number and difficult to interact directly with experts in the field of stone magpie disease are obstacles for bird lovers in solving the problem of determining the type of disease in stone magpies, therefore in the field of information technology there is a system which can transfer expert knowledge into system. The system is an expert system, the system that can make it easier for magpie lovers to determine the type of disease in stone magpies. This research uses the Certainty Factor method with the Forward Chaining supporting method. Based on the results of expert validity testing of the expert system that has been built, the accuracy of the Forward Chaining and Certainty Factor methods is obtained by 90%.