The throat and chest are white or a washed buff color, contrasting with the upperparts and the belly of a very dark blue; the covert feathers are generally clear, blue-gray or purplish.

The blue nuthatch's ecology is poorly known, but it feeds on small invertebrates found on trees; reproduction takes place from April to June or July.

[8] The nuthatches constitute a genus, Sitta, of small passerine birds in the family Sittidae,[9] typified by short, compressed wings and short, square 12-feathered tails, a compact body, longish pointed bills, strong toes with long claws, and behaviorally, by their unique head-first manner of descending tree trunks.

[10] In 2006, ornithologist Edward C. Dickinson Proposed splitting Sitta in multiple genera on the basis of distinct morphological traits.

[11][12] In 2014, Eric Pasquet and colleagues published a phylogeny based on examination of nuclear and mitochondrial DNA of 21 nuthatch species.[fn.

The rectrices, which are the tail's flight feathers, are pale blue in the middle with a black border and contrast sharply with the dark areas of the coat.

[21][22] The species displays no significant sexual dimorphism, but Japanese ornithologist Nagamichi Kuroda describes the female as having slightly duller upperparts.

The species' vocalizations include a melodious tup or tip, a sudden whit, a thin hissing sit, and a fuller, harder, and more forceful chit.

When excited, sit and chit notes are frequently given quickly and repetitively as a chi-chit, chit-chit-chit or chir-ri-rit, which can be prolonged, accelerated into staccato trilling tititititititik, or even becoming a rattling tr-r-r-r-r-r-t. Other calls include a thin, squeaking zhe and zhe-zhe, a squeaky toy-like nasal snieu or kneu, and a buzzy chirr-u.

[24] While prospecting on tree trunks, the bird protects its corneas from falling bark and other debris by contracting the bare skin around its eyes – an adaptation apparently unique to the species.

[24] Little has been specifically reported on blue nuthatch predators, but one individual was seen to freeze during the passage of a prospecting black eagle (Ictinaetus malayensis).

[23] This species lives in the Malay Peninsula (in extreme southern Thailand and northern Malaysia) and in Indonesia on the islands of Sumatra and Java.

[24] In a 1918 expedition by Robinson and Kloss, they commented: "from the commencement of heavy jungle on the valley slopes up to about 8,000 feet on Korinchi Peak this strikingly coloured little Nuthatch was very common, feeding on tall tree trunks in parties of six or seven.

[29] The population has not been rigorously estimated but is considered significant and at low risk, despite BirdLife International's observation that some decline is likely (but not as yet confirmed) due to known destruction and fragmentation of areas the species is known to inhabit.