[2] The variable antshrike was described by the French ornithologist Louis Pierre Vieillot in 1816 and given its current binomial name Thamnophilus caerulescens.

[7][8] Studies involving mtDNA and voice of the Bolivian populations, which is a meeting point for several of the distinctly different subspecies, did not support the theory of several species, instead suggesting that much of the vocal variation is clinal.

[10] Subspecies T. c. cearensis in northeastern Brazil, which also is relatively distinctive, was not included in these studies, and it therefore remains unclear if it is worthy of species recognition.

The subspecies are found thus:[7][11][12][13] The variable antshrike inhabits a variety of landscapes across its range that in general are evergreen forest, secondary woodland, and thickets in more open areas.

T. c. paraguayensis is a bird of the Gran Chaco, where it occurs in dense shrubs and low-stature woodlands along watercourses and in scrubby semi-deciduous forest at elevations between 150 and 850 m (500 and 2,800 ft).

Subspecies T. c. gilvigaster occurs in thick woods along streams and in swampy areas from near sea level to about 1,050 m (3,400 ft).

[7][11][12][13] There is evidence that some migration occurs in the southernmost part of the variable antshrike's range; it is presumed to be a year-round resident elsewhere.

[7] The variable antshrike's diet has not been detailed but is mostly insects and other arthropods; small amounts of seeds and fruits are also eaten.

It hops and creeps through vegetation, gleaning prey from leaves, stems, vines, and branches by reaching and lunging from a perch.

Nests are suspended by their rim from a branch fork, often fairly low to the ground, and often partially to wholly hidden in vegetation.

[7] In an experiment food abundance was shown to influence several measures of reproductive effort, including clutch size.

In general its song is "a simple countable series of usually 6–7 plaintive, evenly spaced whistles of same pitch and intensity".

"[H]owever, the conservation of race cearensis is of concern, since humid forest within its range has been largely reduced to remnant patches...surrounded by sugar cane and other large-scale agricultural development.