The Kauai 'O'o (Kauaʻi ʻōʻō) was a bird species that lived on the islands of Hawaii. Due to habitat destruction by human activities and exploitation, and after humans introduced invasive species to the islands, this bird species went extinct in the late 1980’s. The Kauai 'O'o mated for life and both the male and the female had a distinct mating call. Wikipedia describes it as a very vocal, making hollow, erratic, flute-like calls.
The bird was last sighted in 1985, and the last sound recording was made in 1987. Listen to the last bird of his kind singing a mating call, to a female that would never come.
