The Thick-billed Siskin is a small high-Andean bird with a very broad-based bill. Males have black heads, while females have grey heads; both have yellow rumps.
The male has a black head and throat, a yellow band at the nape, and yellow markings on dark wings. Females lack the black hood and have grey heads and throats. Both sexes have an exceptionally thick bill and yellow rump.
It eats seeds and Polylepis buds, sometimes hanging from branches while feeding. It occurs in pairs or small groups, which may gather into larger flocks outside the breeding season.
An extinction-risk assessment has not been added yet.