Bonin Grosbeak Chaunoproctus ferreorostris (Vigors, 1829)
- RMNH 90732: male. Bonin Islands. Collector: Kittlitz. Syntype of Fringilla Papa Kittlitz, 1831.
- RMNH 90733: female. Bonin Islands. Collector: Kittlitz. Syntype of Fringilla Papa Kittlitz, 1831.
The German naturalist Friedrich von Kittlitz visited many Pacific islands. Several of the insular forms he collected later became extinct. As a result his name is now often associated with extinct birds, such as the Bonin Grosbeak. He was the only naturalist to have seen this grosbeak alive.
Von Kittlitz visited Peel Island in 1828. This island is part of the Ogasawara islands, formerly known as Bonin Islands, south of Japan. Only one year before Von Kittlitz visited Peel, the first Bonin Grosbeaks had been collected by sailors of the British navy vessel HMS Blossom. Von Kittlitz was able to collect several more specimens. In his description of the island he already noted the presence of feral pigs. A permanent settlement was founded in 1830 and goats, sheep, dogs and cats were introduced. This probably led to the extinction of the grosbeak. Like the Bonin Thrush Zoothera terrestris, this bird was a ground dweller, and thus particularly vulnerable to predation by introduced mammals. The American naturalist William Simpson, who visited Peel in 1854, did not find any grosbeaks left, but based on local reports it may have survived until 1890.
Only ten skins of the Bonin Grosbeak are preserved in museums. The Leiden Museum possesses a male and a female, both collected by Von Kittlitz. The other specimens are in Berlin, Frankfurt, St. Petersburg, Tring and New York.