ABSTRACT. We present a new update of the list of birds of the state of Rio Grande do Sul, Brazil, based on a thorough review of new records and evidences accumulated from February 2011 to July 2017. This is the fifth update since the first compilation based on a reasonably complete geographic coverage of the state, published by William Belton in 1978, and the second produced by a regional (informal) committee. It is also the first to widely use citizen science contributions available on shared portals and digital databases on the internet. Forty-three taxa were added, resulting in a final list with 704 species, 6.5% more than in the previous assessment in 2010. Two species were replaced due to taxonomic changes. Documentation for inclusions based on unpublished records is indicated or published here. We also updated the documentation of another 20 species previously included in the list. Inclusions represent mainly migrants recorded in the state as vagrants or irregular visitors (22), but also cases of recent range expansion (especially from the north) and previously overlooked resident or migratory taxa. The average rate of additions (over six species per year) was 30% higher than in the previous period and is expected to accelerate. The percentage of accepted species without documented records in the state decreased from 1.8% in 2010 to 0.7% in the current list. We attribute these results to a better spatial and temporal coverage of the state in recent years, mainly due to the increasing contribution of amateurs, who accounted for 60% of the new occurrences. In contrast, the percentage of species documented by museum specimens has decreased steadily over time (currently at 84%). Investment in scientific research and collection of voucher specimens in the state should keep pace with the growing interest birds arouse in society, due to the importance and usefulness of museum specimens.KEYWORDS. Avifauna, checklist, new occurrence, distribution, documentation.RESUMO. Quatro décadas após Belton: uma revisão de registros e evidências sobre a avifauna do Rio Grande do Sul, Brasil. Apresentamos uma nova atualização da lista das aves do estado do Rio Grande do Sul, Brasil, a partir da revisão de novos registros e evidências acumuladas no período de fevereiro/2011 a julho/2017. Esta é a quinta atualização desde a primeira compilação baseada em uma cobertura geográfica razoavelmente completa do estado, publicada por William Belton em 1978, e a segunda produzida por um comitê regional (informal). Também é a primeira a usar amplamente contribuições da ciência cidadã disponíveis em portais de compartilhamento e bases de dados digitais na internet. Foram adicionados 43 táxons, resultando em uma lista final com 704 espécies, 6,5% a mais do que na versão anterior (de 2010). Duas espécies foram substituídas devido a alterações taxonômicas. A documentação para as inclusões baseadas em registros não publicados é indicada ou apresentada aqui. Também atualizamos a documentação de outras 20 espécies previamente incluídas na lista. ...