[Tweeters] Extinct?

[Dan McDougall-Treacy via Tweeters]

I’m listening to an interview with an ornithologist who is describing his sighting of Black-naped Pheasant-pigeon.
A specimen was described/collected in 1896. Not seen again, nor determined extinct. Sighted by this person in 2002. 
He works in a project called Lost Birds. I haven’t dug more into this; would just like to stimulate interest in the concept.
Dan McDougall-Treacy