J. Yamashina Inst. Ornith., 14: 81-85, 1982 Pterylosis of Some Hawaiian Honeycreepers, Drepanididae Andrew J. Berger* Abstract This paper describes and illustrates the feather tracts in three species of Hawaiian Honeycreepers: Nihoa Finch, Amakihi, and Apapane. The author believes, with others , that the ancestor for the honeycreepers was a cardueline finch, and that this ancestor probably reached the Hawaiian Islands from Asia, and not from North or Central America. Honeycreeper Feather Tracts The endemic Hawaiian honeycreepers (family Drepanididae) have received con- siderable attention during the past decade (Eddinger 1970, Sibley 1970, Richards & Bock 1973, Raikow 1976, van Riper 1980, Berger 1981, Sibley & Ahlquist 1982). However, very little has been published about the pterylosis of this family. Gadow (1890-1899) discussed briefly and illustrated portions of the feather tracts of several species: Palila (Loxiodes bailleui), Kauai Akialoa (Hemignathus procerus), and Kauai Creeper (Oreomystis bairdi). Van Tyne & Berger (1976: 133) illustrated the dorsal feather tracts of the Apapane (Himatione sanguinea). In this paper I present figures of the dorsal and ventral feather tracts of three honeycreepers that Pratt (1979) and Berger (1981) placed in three tribes or subfamilies of this group: Nihoa Finch (Telespyza ultima; subfamily Psittirostrinae), Hawaii Amakihi (Hemignathus virens; subfamily Hemignathinae), and Apapane (Himatione sanguinea, subfamily Drepanidinae). Alar tract. There are nine secondaries, the innermost being the smallest and shortest (Figures 1A, B, C). There are nine functional primaries; the tenth primary is rudimentary and is called a remicle. In the Amakihi, for example, the tenth primary is only 5mm in length, whereas the ninth primary is 47mm long; in one specimen of the extinct Hawaii Akialoa (Hemignathus o. obscurus) the remicle of both right and left wings measured 7.5mm, in contrast to a right ninth primary of 58.5mm and a left of 59.0mm; on a specimen of the Akiapolaau (Hemignathus wilsoni) the two remicles measured 7.25 and 8.5mm, the ninth primaries, 57.0 and 57.5mm. There are only two alular feathers in the three species illustrated in this paper. However, I found three alular feathers in the Hawaii Akialoa, Akiapolaau, the Ou (Psittirostra psittacea), and the Iiwi (Vestiaria coccinea). The humeral tract is well developed and is similar in the three species illustrated. Distinct apteria occur between the humeral tract and the dorsal spinal tract in the Nihoa Finch and the Hawaii Amakihi but this space is covered by regularly spaced feathers in the Apapane. Caudal tract. There are 12 rectrices but only 10 upper tail and 10 under tail coverts. * Department of Zoology , 2538 The Mall, University of Hawaii, Honolulu, Hawaii 96822, USA. 81 82 A. J. Berger Fig. 1. A. Ventral feather tracts of the Nihoa Finch: B. Ventral feather tracts of the Hawaii Amakihi: C. Ventral feather tracts of the Apapane. Pterylosis of Some Hawaiian Honeycreepers 83 Fig. 2. A. Dorsal feather tracts of the Nihoa Finch: B. Dorsal feather tracts of the Hawaii Amakihi: C. Dorsal feather tracts of the Apapane. 84 A. J. Berger The oil gland is well developed and is nude. Dorsal feather tracts. The capital tract occupies the entire dorsal surface of the head; there are no distinct apteria in any of the three species illustrated. The spinal cervical and the dorsal spinal tracts differ among the three species as shown in figures 2-A, B, C. The Nihoa Finch has the most distinct tracts, with large apteria on each side. These apteria are much smaller in the Amakihi and are essentially absent in the Apapane, which is the "most heavily feathered" of the three species. One can postulate that this is an adaptation for the climatic conditions (i. e., frequent heavy rains and often cold nights) found in the mountains of the Hawaiian Islands. The Nihoa Finch is not subjected to such extremes in weather conditions. The most notable feature in the femoral and crural tracts is the much sparser distribution of feathers in the Nihoa Finch. Ventral feather tracts. The interramal region is completely feathered in the Amakihi and the Apapane; marginal apteria on the lateral sides of the interramal feather tract occur in the Nihoa Finch. The finch also has fewer feathers in the ventral tracts so that a midline apterion is conspicuous in the lower cervical region; the lateral abdominal feather tracts end well anterior to the anal circlet of feathers. By contrast, the abdominal feather tracts in the Amakihi and the Apapane extend almost to the anal circlet and the space between the two sternal and abdominal tracts contains many small contour feathers, so that apteria are small and inconspicuous. Discussion For many years, ornithologists postulated that the ancestors of the Hawaiian Honeycreepers were coerebid-like birds that reached the Hawaiian Islands from Central America (Gadow in Wilson & Evans 1890-1899, Amadon 1950). More recently Sibley (1970), Richards & Bock (1973), Raikow (1976), and Sibley & Ahlquist (1982) have presented much more evidence that suggests a cardueline-finch ancestor for the honeycreepers. I have accepted that evidence even though the Drepanididae deserve much more study, both anatomically and biologically (see Berger 1981). I agree with Sibley and Ahlquist that the Cardueline finch ancestor of the Hawaiian Honeycreepers reached the Hawaiian Islands from Asia, and not from North or Central America. Also needed is a thorough study of the pterylosis of a large number of cardueline finches; the figures in Samson's paper (1976) of the feather tracts of the Cassin's Finch (Carpodacus cassinii) do not permit adequate comparison with the honeycreepers. References Amadon, D. 1950. The Hawaiian Honeycreepers (Aves, Drepanididae). Bull. Amer. Mus. Nat. Hist. 95: 151-162. Berger, A. J. 1981. Hawaiian Birdlife, 2nd ed. 67 color plates, 137 black-and-white figures. Univ. of Hawaii Press, Honolulu, 260 pp. Eddinger, C. R. 1970. A study of the breeding behavior of four species of Hawaiian Honeycreepers (Drepanididae). Ph. D. thesis, University of Hawaii, 212 pp. Gadow, H. 1890-1899. Remarks on the Structure of Certain Hawaiian Birds. In Aves Hawaiiensis, S. B. Pterylosis of Some Hawaiian Honeycreepers 85 Wilson & Evans, A. H. 23 pp, 58 figures, R. H. Porter, London. Pratt, H. D. 1979. A systematic analysis of the endemic avifauna of the Hawaiian Islands. Ph. D. thesis, Louisiana State University, Baton Rouge, 228 pp. Raikow, R. J. 1976. The origin and evolution of the Hawaiian honeycreepers (Drepanididae). Living Bird 15: 95-117. Richards, L. P. & Bock, W. J. 1973. Functional anatomy and adaptive evolution of the feeding apparatus in the Hawaiian honeycreeper genus Loxops (Drepanididae). Ornithological Monographs No. 15, American Ornithologists' Union, Lawrence, Kansas, 173 pp. Samson, F. B. 1976. Pterylosis and molt in Cassin's Finch. Condor 78: 505-511. Sibley, C. G. 1970. A comparative study of the egg-white proteins of passerine birds. Peabody Mus. Nat. Hist. Bull. 32: 1-131. Sibley, C. G. & Ahlquist, J. E. 1982. The relationships of the Hawaiian Honeycreepers (Drepaninini) as indicated by DNA-DNA hybridization. Auk 99: 130-140. Riper, C. 1980. Observations on the breeding of the Palila Psittirostra bailleui of Hawaii. Ibis 122: 462-475..