The remiges, rectrices, alula, medium, greater and primary coverts are a dark grey colour with a brown tinge, with bright greyish-green outer edges.

The juvenile resembles the adults, but has looser, fluffier plumage and, possibly as a result of this, slightly less yellow underparts.

It has marginally whiter and more clear-cut pale tips to the greater coverts, and probably slightly more green on the anterior part of the lateral crown-stripes.

Studies of vocalisations and DNA over the last 20 years have increased the number of recognised warbler species by 40% to 64.

At Hin Namno National Protected Area it was found in old-growth and mature secondary semi-evergreen forest on limestone karst, between 280 and 460m.

In the Nadi and Sayphou Loyang areas, Laos, it was found in dry evergreen and semi-evergreen forest and secondary growth on limestone over 600–1000 m. In the Thai An Commune, Ha Giang, it was observed in tall secondary scrub on a well-vegetated slope with a karst landscape at approximately 1200 m.[5] Named limestone leaf warbler because it breeds in Laos's limestone karst environments – a region known for unusual wildlife – it is similar to other warblers in this area of S.E.

“With increased attention from biologists, the Annamite mountain range of Laos in particular is revealing itself as a lost world for new and unusual wildlife.”[9] Scientists presume there are many limestone warblers in this region; however, its habitat contains threats.

WCS is continuing to work with the Lao Government in an effort to reduce the threat to this bird and other wildlife in the area.

[9] The conservation of the limestone leaf warbler depends on its habitat rather than being hunted, due to its small size.

However, some parts of the karst blocks are being cleared for timber, which reduces the extent and quality of forest patches.