Following the recent study of Rabarivola et al. (2007), this species is known from the Ankarana and Analamerana region in the north of Madagascar (although see Banks et al. 2007 who did not record it there), and throughout the Sambirano region in the north-west (and the Ampasandava Peninsula). Rabarivola et al. (2007) also found evidence that the range of this species extends further south in the eastern rainforests than previously believed, occurring in Maraonsetra in the north-east at least to Zahamena, east of Lake Aloatra. Whether these populations are contiguous remains to be determined. Animals from the central-western parts of Madagascar, formerly attributed to H. occidentalis, are now provisionally assigned to H. griseus following Rabarivola et al. (2007).