"Ceratorhina monocerata. Unicorn Auk. Horn-bill Auk. Adults in summer: Bill orange-yellow. Culmen and…
"Ceratorhina monocerata. Unicorn Auk. Horn-bill Auk. In winter: Bill orange-yellow. Culmen and base…
"Ceratorhina monocerata. Unicorn Auk. Horn-bill Auk. Young: Bill like that of adults in winter, lacking…