The Eye Colouring of Australian Corvidae

206 THE S.A. ORNITHOLOGIST THE EYE COLOURING OF AUSTRALIAN CORVIDAE The following correspondence between of the Australasian region and the Jackdaw, Sir John Cleland (Beaumont, S.A.) and Co'rvus monedula. Derek Goodwin of the British Museum Besides the Australian species, the follow­ (Natural History), forwarded by Dr. Eric ing have white to blue irides: Corvus [usci­ Sims, is included with the permission of both capillus (parts of New Guinea, Am Islands), correspondents. Mr. Goodwin in a later C. validus (Moluccas), C. woodfordi (Solo­ letter stressed that he is particularly inter­ mon Islands), and C. tristis (New Guinea). ested in receiving information on the nicti­ All of these have the feather bases either eating membrane of Australian corvids (see white or very pale whitish grey.' last paragraph of his letter). All other Corvus species, including our 1. To The Director, Department of Orni­ Raven, Carrion Crow and Rook, have dark thology, British Museum (Natural History), brown or brownish irides when adult. The Cromwell Road, London SW7. (dated No­ British species, and probably most or all vember 23, 1969). others, have the irides bluish or bluish grey Dear Sir, as nestlings but they soon darken. May I appeal to you for help in the fol­ I agree with you in thinking that the lowing matter? D. L. Serventy and H. M. Australian crows probably developed from a Whittell (1962) in their book, Birds of Wes­ common ancestor. There may, of course, tern Australia (Paterson Bokensha Pty., have been successive invasions from New Perth, W.A.) state that "all our members of Guinea, if the white or bluish-eyed proge­ the genus Corvus have brown eyes in imma­ nitor evolved there first. What surprises me turity and white in adult life." From this I is that in the course of speciation within infer that a white iris is a genetic charac­ Australia none of your species has re­ teristic of Corvus in Australia. I under­ developed a dark eye as a species character, stand from H. T. Condon, the ornithologist especially as all have dark eyes when imma­ at our South Australian Museum, that there ture. is no mention (in the sources available to I think that white or dark grey feather him) of the iris becoming white in your bases are relatively labile characters in mature English carrion crows and ravens. I Corvus and that some species with white would be pleased to know the iris colour of feather bases are most closely allied to others these birds in your coun try and I would be with dark feather bases. very grateful for any information that you Coming back to the white or whitish iris. might also have about the eye colour in Although the Jackdaw has silvery white or Corvus elsewhere in the world, especially in silvery grey irides when adult, the very Indonesia and New Guinea. closely-allied Daurian Jackdaw, C. dauricus, If a white iris is confined to the four has dark irides. The jackdaws form a very species of Corvus in Australia, it must surely discreet little group within Corvus and cer­ mean that these four species are descended tainly have no close affinities with the Aus­ from a common ancestor who developed a tralian species. They are sometimes put in mutation in this direction which also led a separate genus Coloeus. to descendants with both white and grey Some (or all?) of the dark-eyed species bases to the feathers. This possibility in­ of Corvus draw the white nictitating mem­ trigues me; can you help me? brane over the eye in many agonistic or .... SIR JOHN CLELAND. sexual situations. Indeed when in Australia 2. To Sir John Cleland, (dated December I at first kept getting the impression of crows 9, 1969). flying about with nictitating membranes Dear Sir, permanently drawn over the eye! It would Dr. Snow has asked me to reply to your be most interesting to learn whether the query, as I am working on a monograph Australian or other white-eyed species also of the Corvidae. draw the nictitating membrane over the eye There are one or two little-known island in some displays and what colour it is. Inci­ crows for which iris colour does not appear dentally, in our Magpie, Pica pica, the nicti­ to have been reported. With these possible tating membrane is still more conspicuous; (but improbable) exceptions, a white, silver, being bluish white with a brilliant orange pale grey or blue iris seems confined to crows spot on it. DEREK GOODWIN.