It forms a superspecies with the Many-colored Bushshrike (T. multicolor) and the two are sometimes considered to be a single species.
It is closely related to the Streaked Fantail of the rest of Fiji, and forms a superspecies with the numerous island species of fantail ranging from the Solomon Islands (the Brown Fantail) to Samoa (the Samoan Fantail).
There are several other taxonomically unclear examples that belong in the same superspecies complex, such as Yellow-legged Gull (L. michahellis), Glaucous Gull (L. hyperboreus), and Caspian Gull (L. cachinnans).
It forms a superspecies with Eurasian Sparrowhawk (A. nisus) and possibly Madagascan Sparrowhawk (A. madagascariensis) (Ferguson-Lees and Christie 2001).
The Sinaloan Crow (Corvus sinaloae) appears to be genetically extremely close to this bird and can be considered the western form of it though the voice is quite different, indeed a third species, the Fish Crow (Corvus ossifragus) of the southeastern United States appears to be very closely related to them also and the three may be considered a superspecies.
mtDNA cytochrome b and NADH dehydrogenase subunit 2 sequence data (Voelker, 2002) is of limited use: the suspicion that there is a superspecies of probably 3 white-bellied, black-throated wagtails is confirmed.