“No-one has seen the Yellow-crested Helmetshrike for about 20 years.”
That’s a bold statement. In order to arrive at that conclusion, they would have to have asked “everyone”. I doubt that happened, because they didn’t ask me.
No one in their little club of bird geeks has publicly stated that they’d seen one. That’s entirely different.
Not everyone is a bird watcher...in fact....most aren’t unless they’re cra***** on you car.