The site includes forest catchments and lowland valleys through to montane forest. Both Mount Popomanaseu and Mount Makarakomburu are included within the site - the highest mountains in the Solomon Islands.
Three of the montane species are endemic to the island, Guadalcanaria inexpectata, Myzomela melanocephala and Zoothera turipavae, while 3 other species occur only here and in Bougainville, PNG and 1 is also associated with the high mountain range of Espiritu Santo, Vanuatu. The lowland forests contain Centropus milo, Columba pallidiceps and Lorius chlorocercus, while there have been a number of recent sightings of Nesoclopeus woodfordi on Guadalcanal.
Non-bird biodiversity: 1 species of endemic montane snail species. Species of monkey-faced bat (Pteralopex pulchra) is known from only one specimen.
BirdLife International (2019) Important Bird Areas factsheet: Guadalcanal Watersheds. Downloaded from http://www.birdlife.org on 23/09/2019.