Washington -- The numbers of African gorillas have increased thanks to conservationists collaborating in three countries where they are found, wildlife advocates say.
A census in the Virunga Massif, where most of the world's mountain gorillas live, revealed 480 individuals living in 36 groups, the BBC reported Tuesday.
Thirty years ago only 250 gorillas survived in this same area, conservationists say.
Three contiguous national parks are found within the Virunga Massif: Parc National des Virunga in the Democratic Republic of Congo, Volcanoes National Park in Rwanda and Mgahinga Gorilla National Park in Uganda.
Conservationists credit the increase in gorilla numbers to collaborative "transboundary" efforts by organizations in the three countries.