The Half-collared Sparrow inhabits the understory of montane forest and secondary growth in southeastern Brazil. Males have a yellow lower mandible and a broken breast band. A 2022 report recorded one bird singing at a forest edge.
About 15 cm long. The male has a bicolored bill with a yellow lower mandible, a broken breast band, dark grey flanks, and no yellow shoulder patch. The female also has a broken breast band.
The account says it scratches through leaf litter. A paper reports one bird spontaneously singing on 2 August 2022 at a forest edge with flowering Chusquea in Saí, Santa Catarina.
An extinction-risk assessment has not been added yet.