'avifaunistic' originates from modern English formation combining 'avifauna' and the adjectival suffix '-istic'. 'Avifauna' itself is built from Latin 'avis' meaning 'bird' (via the combining form 'avi-') plus Latin 'fauna' meaning 'animal life'. The suffix '-istic' comes via Greek/Latin ('-isticus') meaning 'pertaining to'.

'avifaunistic' developed from the 19th-century coinage 'avifauna' (a hybrid of Latin 'avis' + 'fauna') and subsequently took the common adjectival suffix '-istic' to form 'avifaunistic' in modern English.

Initially the components meant 'bird' (from Latin 'avis') and 'animal life' (from Latin 'fauna'); combined as 'avifauna' they meant 'the birds of a region', and 'avifaunistic' has come to mean 'pertaining to those birds'—a meaning that has remained specialized and consistent.