Key to Subspecies.
A. Lower plumage pale rufous or albes¬cent rufous.
a. Rump and upper tail-coverts of practically the same colour throughout
a1. Wing 120 mm. or over.
a2. Shaft-streaks on rump absent or obsolete; lower plumage decidedly tinged with rufous, with fine striations…………H. d. daurica, p. 248.
b2. Shaft-streaks on rump distinct; lower plumage nearly white, with coarse striations …………H. d. striolata, p. 249.
b1. Wing under 120 mm.
c2. Striations on lower plumage much wider than the shafts……H. d. nepalensis, p. 250. d2, Striations on lower plumage hardly broader than the shafts…………H. d. erythropygia, p. 251
Rump paler posteriorly and becoming creamy-white on the upper tail-coverts…………H. d. rufula, p. 252.
B. Lower plumage chestnut…………H. d. hyperythra, p. 253.
The inter-relationship of these various forms still requires elucidation. Thus in the area South of the Brahmaputra where E. d. nepalensis is said to breed, but where I have never seen it, we have two forms of H. daurica breeding. H. d. daurica is a regular breeding bird during August and September, rarely July, whilst H. d. striolata is an irregular visitor breeding in April and May and again leaving the country before H. d. daurica arrives. In this Province H. d. daurica breeds in human habitations only, whereas H. d. striolata is purely a cliff builder. It is possible that both these forms are merely visitors from their normal breeding haunts, which do not overlap. More specimens, obtained when nesting, are required from China, Assam and the intervening countries.