The Ultramarine Grosbeak is a widely-distributed denizen of forest, scrub and disturbed habitats throughout the lowlands of eastern South America between the Amazon bazin and the Patagonian steppe; with disjunct populations in Venezuela and Colombia. The Ultramarine Grosbeak is sexually dimorphic, with the males showing a deep, rich blue color to the plumage with a pale supercilium and malar, and black lores. The female is
uniformly chocolate-brown. Both sexes show a large, thick bill with a pale base to the mandible. Two subspecies are currently recognized, which segregate by habitat: C.b.argentina, which occurs in shrub, and C.b. sterea, which inhabits forests, and is smaller than C.b.argentina. this species is more commonly heard than seen, as it can inhabit thick patches of scrub and be reclusive at times, but sings a loud, far-reaching song.