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Drongo Cuckoo - justification for split? (1 Viewer)

James Lowther

Well-known member
hello all,
I am hoping to travel to Nepal next year and trying to get ahead of the curve on various taxonomic issues.

However, Drongo Cuckoos have left me completely stumped. I don't know if i have ever seen a more confusing taxonomic knot.

Putting aside Moluccan and Philippine species, the Fork-tailed vs Square-tailed split seems to be divided up in radically different ways depending on what you read.

According to Birdlife datazone (which should be the same as HBW??),

Square-tailed S.lugubris s.s. is largely restricted to the Greater Sundas, plus Palawan, the Thai-Malay peninsula up as far as SC Myanmar, and a couple of outlying areas in NE India and neighbouring countries.

Fork-tailed S.dicruroides occurs as a breeding species in Sri Lanka, India and a wide swathe of the Sino-himalayan region from Kashmir across to Fujian

In IOC by contrast, Fork-tailed (subspecies dicruroides and stewarti) is restricted to Sri Lanka, India and the "Himalayan foothills", with the species occurring in the great swathe from Kashmir to Fujian seemingly being Square-tailed (subspecies lugubris, brachyurus and barussaram). This does have the unfortunate effect that possibly both species occur in Nepal.

Normal conclusion here would be that the different lists split up the subspecies differently. However, this does not appear to be the case. Once you start looking at the treatment of subspecies things become even more of a mess.

Just a couple of examples:-

according to IOC the populations in the NW Himalayas and Borneo both belong to the same subspecies i.e. brachyurus. However, according to Birdlife these populations do not even belong to the same species!

On the other hand, Eaton et al Birds of the Indonesian Archipelago (at least the first edition) states that the subspecies breeding on Borneo is lugubris!

Anyway, i am pretty sure there is no way to resolve these different treatments neatly, there does not appear to be any logic to it, just a mess.

What i am interested however, is what the actual justification for this split is? The only paper i've tracked down so far is this one

which provides justification on vocal grounds for the split between Mainland and Greater Sunda forms on the one hand and Philippine and Moluccan forms on the other. But says that there are no vocal differences amongst the former group, with recordings from Nepal, Thailand, peninsula Malaysia, Borneo and Palawan compared.

Xeno-canto seems to bear this out.

So, what gives?? Where is the original justification for the split and what evidence does it put forward?


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