The Crossley's Babbler (Mystacornis crossleyi), also known as Crossley's Babbler-vanga or Madagascar Groundjumper is a bird species in the family Vangidae. It is in the monotypic genus Mystacornis. The species was once placed in the Old World babbler family Timaliidae and its position with the vangas is still not universally accepted. It is endemic to Madagascar. It is distributed in the east of Madagascar in broadleaf forest, from sea level up to 1800 m.
Crossley's Babbler is a small babbler-like bird, 15 cm long and weighing around 25 g. Its most distinctive feature is the olive-grey bill, which is disproportionately long and slightly hooked at the end. The plumage of the male is olive green on the crown, back, wings, tail and flanks, a grey belly, black throat and face, with a white submoustachial stripe and grey stripe above the eye. The legs are grey and the iris black. The female is similar but with a white throat and belly.
The Crossley's Babbler forages singly or in pairs. It is a terrestrial bird that feeds on the ground on spiders, cockroaches, earwigs, true bugs, grasshoppers and ants. It rarely flies but instead walks and runs and probing its bill into leaf-litter, mosses, and soil.
The breeding season for this species is from August to November. The male builds a shallow cup nest of twigs and rootlets ina tree or other vegetation around 1.5 m off the ground. Two to three eggs are laid and incubated by both sexes.