The island of Sangihe, Indonesia, was visited in 1998–99 with the
aim of producing population estimates of the island's endemic and other
restricted-range bird species, some of which were poorly known and thought
to be at risk of extinction due to habitat change. The study focused on the
last remaining patch of primary forest, on Mount
Sahendaruman in southern Sangihe, home to three critically endangered
endemic species: Cerulean Paradise-flycatcher Eutrichomyias
rowleyi, Sangihe Shrike-thrush Colluricincla sanghirensis,
and Sangihe White-eye Zosterops nehrkorni. Population densities
were estimated from primary forest and secondary habitats across Sangihe to
assess species dependency on primary habitat. Twenty of 24
restricted-range, globally threatened or endemic taxa were recorded and
density estimates were calculated for 15 of these. The endemic Red-and-blue
Lory Eos histrio is extinct on Sangihe as a result of lowland
forest loss. Six species (Nicobar Pigeon Caloenas nicobarica,
Sulawesi Dwarf Kingfisher Ceyx fallax, Golden Bulbul Ixos
affinis, E. rowleyi, C. sanghirensis, and Z. nehrkorni) were
either not recorded or have very
small populations and are critically endangered on Sangihe; two species of
Tanygnathus parrot are also facing local extinction on the island.
The major threat to all these species is the destruction of primary forest;
larger species are also threatened by hunting. The remaining endemic and
restricted-range species (Blue-tailed Imperial Pigeon Ducula
concinna, Sangihe Hanging-parrot Loriculus catamene, Sangihe
Scops-owl Otus collari, Lilac-cheeked Kingfisher Cittura
cyanotis and Elegant Sunbird Aethopyga duyvenbodei) were more
widespread and occurred in secondary habitats. I recommend that L.
catamene and A. duyvenbodei, currently treated as globally
endangered, be reclassified as near-threatened and vulnerable respectively because of their large populations
and tolerance of disturbed habitats. Species with wide global ranges that
are represented by endemic subspecies have the greatest tolerance for
disturbed habitat. The widespread deforestation of Sangihe has had serious
consequences for many bird species and today the island supports the most
threatened assemblage of single-island endemic species in Indonesia.
Species-specific research to determine the status and ecology of E.
rowleyi, C. sanghirensis and Z. nehrkorni, and monitoring of
the Sahendaruman forest are desperately needed as a basis for future
conservation efforts.