Taxonomy and Systematics
The Old World babblers are a large family of passerine birds characterised by soft fluffy plumage. They are birds of tropical areas, with the greatest variety in southeast Asia. This species is very close to the Sri Lanka Scimitar Babbler which has in the past been treated as a subspecies. In the past, this species has been considered as a subspecies of the White-browed Scimitar Babbler (Pomatorhinus schisticeps) which is found along the Himalayan foothills. Molecular studies confirm this relatedness.
There are several races that have been noted, race travancoreensis is found in the Western Ghats south of Goa and is darker (see Gloger's Rule). The nominate horsfieldii is found in the plains in the southern part of the peninsula. The race obscurus of the dry zone in the northwest (Madhya Pradesh, Rajasthan and Gujarat; possibly Orissa) is lighter and greyer. Race maderaspatensis of the Eastern Ghats is intermediate in plumage between the nominate form and obscurus. Race maderaspatensis lacks the black base to the upper mandible and the bill is shorter. It has been recorded from the Palkonda Hills, Nallamalai Hills, Kurumbapatti and Shevaroy Hills.
The Sri Lankan form that was considered as a subspecies melanurus but has been elevated to a full species by recent works that note the geographic isolation and distinctive calls. The Sri Lankan forms however appears to respond to the call of the Indian form and may need further study.
Read more about this topic: Indian Scimitar Babbler