From the Reise der österreichischen Fregatte Novara [...] Zoologischer Theil, A. Pelzeln, "Vögel":

"An individual was caught in March by Purser Basso off the island of Kondul. Red-yellow iris. A female was brought on board alive from the island of Gran Nicobar. A rare and shy bird from the two islands of Kondul and Gran Nicobar, where it resides in the highest treetops. The inhabitants of Nicobar call it, like the previous species, Taleka. Zelebor.
The aforementioned female of Gran Nicobar, whose sex was confirmed by examination, has a red upper beak. This beak colouration seems to be common to older individuals of both sexes." (p. 98)