The russet-bellied spinetail (Synallaxis zimmeri) is a Vulnerable species of bird in the Furnariinae subfamily of the ovenbird family Furnariidae.

Adults have a faint gray-white supercilium, a distinct but broken white eyering, and blackish lores on an otherwise gray face.

It inhabits arid woody scrublands characterized by dense stands of short, thorny, trees and shrubs.

[3] The IUCN originally assessed the russet-bellied spinetail as Threatened, then in 1994 as Endangered, and since late 2020 as Vulnerable.

It has a small range and its estimated population of 600 to 1700 mature individuals is believed to be decreasing due to habitat destruction.

"Dense undergrowth habitat within its range is severely degraded by grazing of cattle and goats, and is cleared for agricultural expansion and plantations.