The gray-backed tailorbird (Orthotomus derbianus) is a species of bird formerly placed in the "Old World warbler" assemblage, it but now placed in the family Cisticolidae. It is endemic to the Philippines found only on the islands of Luzon and Catanduanes.
Ebrd describes this species as "A small, long-billed, long-tailed bird of dense tangled undergrowth in lowland forest in southern Luzon and neighboring islands. Has olive-green wings, a pale belly, a gray back and rump, a gray chest and throat with streaks, a rufous cap and tail, and orange legs. Very similar to Green-backed Tailorbird, but has a gray back, throat, and lower belly. Voice includes an explosive note followed by a rattling trill: “plik! Brrrrrrrrrr!”[1]
Two subspecies are recognized:
In 1958, a specimen was collected on Palawan and there have been no records on the island since. It is presumed to be a result of some aberrant movement or an error.
It is known to feed on small inverterates. Usually seen foraging in dense undergrowth, typically in pairs. There is no breeding information on this bird aside from a reported nest in March. [2]
It is endemic to the Philippines, ranging across most of the islands. Its natural habitats are tropical moist lowland forest and tropical moist montane forest as high as 2,480 meters above sea level.
It is assessed as a Least-concern species by the International Union for Conservation of Nature as it is fairly common in its range and tolerant of disturbed habitat.