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

"Captured by B. Wüllerstorf on 20 June on the marshy shore of Laguna de Bai near Los Baños. Iris cherry red. Frontal lobe and beak scarlet, the latter lemon-yellow at the extremities. Legs yellow-greenish-grey, turning brown towards the nails. Claws light brown. A very young bird of this species has been preserved in alcohol. Zelebor." (p.135)