Cettidae – Bush Warblers, Tesias & Allies

Cettiidae is a newly validated family of small insectivorous passerines broadly described as warblers. It was formerly placed in the Old-World warbler ‘wastebin’ assemblage. It contains the Cettia (typical bush warblers) and their relatives. As a common name, cettiid warblers is usually used. Some taxonomic authorities have included this entire family, along with the related genera Erythrocercus and Scotocerca, in an enlarged family Scotocercidae. However, the family Erythrocercidae is now recognised as a stand-alone family for the genus Erythrocercus based on divergence in multilocus and genomic DNA data, supported by behavioural differences. Scotocerca, however, is now combined with Cettia and relatives in the family, Cettiidae.

Its members occur mainly in Asia, ranging into Oceania in the east and Europe in the west. The pseudo-tailorbirds, tesias and stubtails, as well as Tickellia and Abroscopus warblers, are mostly found in the forests of south and southeastern Asia, with one species of stubtail reaching as far north as Japan and Siberia.

Cetti’s Warbler Cettia cetti – ©Ashley Beolens

Only one species, Neumann’s Warbler Hemitesia neumanni, occurs in Africa. The range of the genus Cettia extends west to Western Europe, while that of Horornis extends well into the Pacific, as far as Fiji and Palau. Most of the species in the family are sedentary, but the Asian Stubtail is wholly migratory and the Japanese Bush Warbler and Cetti’s Warbler are partly migratory over much of their range. A few species, such as the Pale-footed Bush Warbler, are altitudinal migrants.

Bornean Stubtail Urosphena whiteheadi

The species are small, stubby birds. Most have moderately long to long tails, while the stubtails and tesias have tiny tails that do not even emerge past their tail coverts. The group is typically clad in dull plumage, often with a line above the eye, but some are more colourful. Altogether the Cettiidae are a quite variable group containing many aberrant birds that hitherto had been uncomfortably placed with a wide range of unrelated families. By contrast, the Locustellidae, which contain birds which appear very similar to many cettiids, are far more uniform. Most live in scrubland and frequently hunt food by clambering through thick tangled growth.

Tanimbar Bush Warbler Horornis carolinae

The family Cettiidae was (2006) named as a tribute to the Italian scientist and mathematician Francesco Cetti. Most are secretive LBJs (Little Brown Jobs), adept at clambering through thick shrubbery, and, though vocal, some will not emerge even in response to playback. Although some genera forage actively in mid and upper levels of vegetation, most forage near the ground and many will not flush if alarmed, instead escaping by walking or scurrying away like a mouse.

Aberrant Bush Warbler Horornis flavolivaceus

The tesias and stubtails are the most adroit at running through dense vegetation seemingly without disturbing it at all, and with their short tails, relatively long legs, and bounding gait they look like tiny pittas making their getaway.