'avifauna' originates from Modern Latin, specifically the compound of Latin 'avis' and 'fauna', where 'avis' meant 'bird' and 'fauna' meant 'animal life'.

'avifauna' was formed in New Latin (Modern Latin) as the compound 'avis' + 'fauna' and was later adopted into English as 'avifauna' with the same sense.

Initially, it meant 'the bird fauna of a particular region or period', and this meaning has remained largely unchanged.