Scarce and local throughout its range, and rarely encountered. Found in varied scrubby montane habitats, especially Polylepis groves. Feeds in shrubs and on the ground, often in pairs and small groups; associates readily with other siskins. Both sexes resemble the much commoner and more widespread Hooded Siskin (absent in central Chile), but Thick-billed Siskin is stockier with a relatively large, deep bill. Varied songs and calls overall rather similar to other siskins.