on the kagu: The kagu’s affinities are not well resolved. It was long one of the most enigmatic birds and in more recent times is usually affiliated with the Gruiformes (cranes). It was initially classed as a member of the clade Ardeidae (herons) because of the presence of powder down, similarities in plumage colour and internal anatomy, the colour of the chicks and eggs, and the change in colouration of the chick as it grows. When seen as a gruiform, the kagu is generally considered related to the extinct adzebills from New Zealand and the sunbittern from Central and South America. Recent studies do indicate that the sunbittern is the closest living relative of the kagu.
With the recent revisions going on
at ReptileEvolution.com in the higher bird clade the kagu (restricted to the island of New Caledonia) now nests with the tern (Indo-Pacfic oceans, including breeding on New Caledonia and along the coasts elsewhere). And now we know how the kagu got to New Caledonia in the first place. More data (Fig. 2) and a closer examination of existing data are making these moves.
Thalasseus bergii (aka: Sterna bergii; Lichtenstein 1823; 50cm tall) is the extant greater crested tern is a sea bird capable of flying great distances and feeding by plunge diving. Terns are traditionally related to gulls, skimmers and skuas. Here the resemblance toRhynochetos extends to the head crest.
Rhynochetos jubatus (Verreaux and DesMurs 1860; 55cm in length) is the extant kagu, a nearly flightless sea gull restricted to New Caledonia. The rostrum tips down and is sharp. ‘Nasal corns’ (soft structures covering the nostrils) are a unique feature presumably developed to prevent dirt from entering. Perhaps these were originally developed by the extinct tern ancestor that used them to prevent water from entering during dives. ‘
Lichtenstein M 1823. Published in:Lichtenstein, H. 1823, pp. x 118 pp., Königl. Universität, Berlin
Verreaux JP and des Murs O 1860. Descriptions d’Oiseaux nouveaux de la Nouve.-Calédonie.