In 2006–07, researchers from the Wildlife Conservation Society studied gorillas in heavily forested regions centered on the Ouesso district of the Sangha Region. They suggest a population on the order of 125,000 Western Lowland Gorillas, whose isolation from humans has been largely preserved by inhospitable swamps.
Where did researchers study chimps in heavily forested regions?
{'text': 'Ouesso district', 'answer_start': 124}