This taxon is Not Recognised as a species by BirdLife International.
Zosterops poliogaster (Sibley and Monroe 1990, 1993) was split into Z. poliogastrus, Z. kulalensis, Z. winifredae and Z. silvanus by Collar et al. (1994) but the minor plumage differences are not considered sufficient to warrant this treatment, which is no longer adopted by the BirdLife Taxonomic Working Group.
BirdLife International (2016) Species factsheet: Zosterops kulalensis. Downloaded from http://www.birdlife.org on 04/12/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/12/2016.