The last one in my week of Hawaiian birds for now.
These have only ever been seen three times, all by George C. Munro. He first saw one in 1913, thought it was a different kind of bird and shot it. He could not tell if it was a male or female (he said it was hard shot, which I'm unsure about but I assume it means it was a bit too destroyed). Most likely the specimen was a girl because it was a bit drab. He had never heard their calls before, and not seen any with similar markings, but especially had never seen a beak like this one had. He seemed to think it might be a deformation and really wanted to get others to compare. He did see them two more times, once in 1916 and once in 1918, but was unable to see their beaks. None were seen other than those three times, and other than the first one, none were caught. Starting in 1900, most of the area was converted into pineapple fields, and it was likely close to extinction when he saw them originally. Avian Malaria didn't come to the area until the 1920's, so if any were remaining, that could have potentially been what caused the final extinction. Although it seemed to have just been eating berries, the hypothesis was that assuming the beak was not deformed, maybe it was to help with getting snails from shells.
I find it interesting that none of the information I saw compared the hookbill to the Maui Parrotbill because to my eye the markings as described are more like that bird. The beak is also similar to the parrotbill, more so than the ʻōʻū Munro thought he was shooting. Granted, I haven't seen any of these birds in real life, but based on what I've seen and read now, my first thought would be that it was a deformity and that it was a different species of the parrotbill. Both the ʻōʻū and parrotbill are species of honeycreepers though actually. I don't know, it would be interesting to look into it more. So many species have been lost forever, I suppose it doesn't really matter if a lost species was more closely related to one bird or another in the grand scheme of things. Gone is gone still, even with all the talk some people do of trying to clone extinct species.