In the past, Rufous Limestone-babbler had been only a subspecies of Limestone Wren-babbler (Turdinus crispifrons calcicola), despite; its colour and distribution range are obviously separated from the others in Turdinus crispifrons.
Recently BirdLife have elevated a subspecies of Limestone Wren-babbler, Turdinus crispifrons calcicola, to a new bird species of the world named as Rufous Limestone-babbler (Turdinus calcicola) which has a brown upper part and rufous brown on cheeks, breast, and belly.
Whereas the other subspecies, which has greyish brown on its body, has been renamed as Greyish Limestone-babbler (Turdinus crispifrons).
Moreover, Rufous Limestone-babbler can be found only on limestone mountain in Saraburi Province and boundaries, in NE of Thailand. Therefore it implicitly becomes a new endemic species of Thailand. Due to its extremely-narrow distribution range and trend to decrease, Rufous Limestone-babbler is also classified as one of Vulnerable Species in the IUCN Red List.
On the other hand, Greyish Limestone-babbler has more extensive distribution range on limestone mountain in West and North part of Thailand, and also in SE Myanmar, N Laos, N Vietnam, and S China.
In addition to the narrow distribution range, Habitat Loss is also a major concern for this species, due to limestone mountain is continuously destroyed for Cement Industry. In the near future, the conservative status of Rufous Limestone-babbler might become more severe unless a good area protection and conservation method.