'avifaunae' originates from New Latin, specifically as the plural form of 'avifauna' (from Latin 'avis' meaning 'bird' + Latin 'fauna' meaning 'animal life').

'avifauna' was coined in New Latin (late 19th century) from Latin elements 'avis' + 'fauna'; the plural 'avifaunae' follows a classical Latin-style pluralization and has been used in scientific contexts.

Initially coined to denote the bird life of a region, its meaning has remained essentially the same and 'avifaunae' functions as a plural or classical plural form referring to such assemblages.