The Dusky Spinetail occurs along the eastern Andean slopes, in humid montane forest edges and dense growth in disturbed places. A nest and nestlings were studied in secondary growth near farmland in eastern Ecuador.
PeruAves describes adults as mostly dusky grey, with a rufous crown, folded wings and tail, and a dark throat. It distinguishes juveniles by their brown head and lack of the rufous crown.
A nest studied in eastern Ecuador was in secondary growth at 950 m. Two adults fed two nestlings, and one visit recorded an adult carrying a snake skin.
An extinction-risk assessment has not been added yet.