The last few weeks, I photographed 2 adult males Red-flanked Bluetails at the Botanical Gardens (Hanoi). They were quite different: one had dark blue (Prussian blue) upperparts and shining blue eyebrow; the other one had lighter blue upperparts and white eyebrow.
After some research it appears that they belong to 2 sub-species, respectively rufilatus and cyanurus. But recently, rufilatus has been elevated to species rank as Himalayan Bluetail (Tarsiger rufilatus) on the basis of its more intense blue colour and its migratory behaviour (short-distance altitudinal migrant, not a long-distance migrant). A patch tick and a lifer for me!
Photos taken on Nov. 19, 2012.