Taxonomy
T. albicollis sometimes includes the members of the T. assimilis group as subspecies, in which case the "combined species" is referred to as the White-throated Thrush (a name limited to T. assimilis when the two are split). Published evidence supporting either treatment is weak, but most recent authorities have followed the split.
On the contrary, it has been suggested that the nominate group and the phaeopygos group of T. albicollis should be considered separate species, but the voices of the two are similar, and the subspecies crotopezus from the nominate group approach members of the phaeopygos group in both plumage and colour of bill. If the two groups are split, the common name Rufous-flanked Thrush has been suggested for T. albicollis, with T. phaeopygos retaining the common name White-necked Thrush or being renamed Grey-flanked Thrush.
Read more about this topic: White-necked Thrush