This ornithological research is in line with the COBIMFO project: this survey fits in an interdisciplinary terrestrial study to investigate relationships between forest carbon stocks and biodiversity in pristine and intervened dense tropical forest of the Congo Basin. Therefore, our focus is generally on the presence and abundance of different bird species in the understorey (based on mist-netting) and particularly on demography and morphometry of some Pycnonotidae species as bioindicators for habitat integrity at the Yangambi MAB Reserve.