Following the European Bird Directive (79/409/EEG), re-stocking with wild-caught chaffinches (Fringilla coelebs) in Flanders has been strongly regulated since 1990. The Government thereby financially supports the breeding of chaffinches, which has led to a significant increase in the number of bred individuals. This project estimates the chance of inbreeding in the absence of re-stocking with wild-caught chaffinches. Genetic variability (estimated with micro-satellite DNA markers) of bred populations will be compared with representative samples of wild-caught individuals. Rates of loss of genetic variability under different scenarios of exchange between breeders and re-stocking are estimated through computer simulation.