Cyanocorax caeruleus occurs in south-east Brazil (south São Paulo south to Rio Grande do Sul), north-east Argentina (Misiones and north Corrientes). A small number of records exist for Paraguay^1,2,5,7, but these are not considered credible⁹. It is rare to locally common up to 1,000 m in lowland evergreen, southern temperate, white-sand and secondary forest and, at least seasonally, is most numerous in Araucaria forest^6,7,8. Populations have apparently declined substantially, particularly in the west of its range, and is now most common in south-east Brazil⁷. Agricultural conversion and deforestation for mining and plantation production historically threaten its habitat, with current key threats from urbanisation, industrialisation, agricultural expansion, colonisation and associated road-building^3,4.