Pacific Science (1987), vol. 41, nos. 1-4 © 1988 by the University of Hawaii Press. All rights reserved

Japanese White-eye, an Introduced , Visits the of Clermontia arhorescens, an Endemic Hawaiian Lobelioid1

THOMAS G. LAMMERS,2 STEPHEN G. WELLER,3 AND ANN K. SAKAI4

ABSTRACT: The Hawaiian Lobelioideae () are generally believed to have adapted to pollination by endemic passerine belonging to the Drepanidinae (Fringillidae) and Meliphagidae. The widespread of many of these birds has raised concerns about the continued survival of the Hawaiian Lobelioideae. During July 1985, the Japanese White-eye (Zosterops japonica Temminck & Schlegel, Zosteropidae), was observed visiting the flowers ofone ofthe endemic lobelioids, Clermontia arborescens (H. Mann) Hillebrand. These observations suggest that the Japanese White-eye may be a potential replacement pollinator for at least one of the Hawaiian lobelioids.

THE LOBELIOIDEAE (CAMPANULACEAE) are range reductions and population declines represented in the Hawaiian Islands by seven (Berger 1981, Scott et al. 1985). Because of genera and 108 endemic of woody these widespread , visitation found primarily in wet montane forests of ornithophilous flowers may be much less (Lammers, in press). The Hawaiian lobelioids frequent today than in the past. In a prelimi­ are generally believed to have adapted to nary attempt to ascertain the current extent of pollination by native nectarivorous passerine bird visitation in Hawaiian lobelioid species, birds (Rock 1919; Porsch 1930; Spieth 1966; we observed a population of Clermontia arbo­ Carlquist 1974, 1980). The ornithological rescens (H. Mann) Hillebrand on Maui for literature contains numerous reports [sum­ visits by potential pollinators. marized by Cory (1984) and Lammers and Freeman (1986)] which describe visits to lobelioid flowers by endemic species of Meli­ METHODS phagidae and Fringillidae subfamily Drepani­ dinae (Table 1). Recent data from nectar-sugar Observations were made along the East compositions (Lammers and Freeman 1986) Maui Irrigation Company's Waikamoi Flume support this hypothesis of ornithophily. in the Ko'olau Forest Reserve on the north Unfortunately, much ofthe native avifauna slope of Haleakala, East Maui. The flume is extinct or in imminent danger of extinc­ runs along the contour of the mountain (ele­ tion (Greenway 1967, Berger 1981, Whitlock vation 1300 m) .from Haipuaena Stream to 1981). Approximately half of the historically Waikamoi Stream. The surrounding vegeta­ known nectarivorous are extinct or tion is wet native forest dominated by 'Ohi'a­ presumed so, and surviving taxa have suffered lehua (Metrosideros polymorpha Gaudich., Myrtaceae). Populations of severallobelioids occur here, including Clermontia arborescens, aculeatiflora Rock, C. bishopii Rock, I This research was supported by NSF Dissertation Improvement Grant 8313285 to TGL (T. F. Stuessy, C. hamatiflora Rock, C. macrostegia Hil­ principal investigator). lebrand, and Trematolobelia macrostachys 2Department of Botany, The Ohio State University, (Hook. & Am.) A. Zahlbr. The population of 1735 Neil Ave., Columbus, Ohio 43210-1293. Clermontia arborescens numbered nearly a 3 Department of Biological Sciences, University of Illi­ nois at Chicago, Box 4348, Chicago, Illinois 60680 . hundred individuals in the immediate vicinity 4 Department of Biology, University of Chicago, Chi­ ofthe flume. This was the only10belioid species cago, Illinoi s 60637. flowering at the time ofour observations. Spieth 74 TABLE I' ENDEMIC BIRDS THATHAVE BEEN REpORTED TO FEED ONFLORAL NECTAROF HAWAIIAN LOBELIOIDEAE (CAMPANULACEAE). In mo st cases, the is identifi ed only as a " lobelioid." Nomenclature follows Greenway (1968) for Drepanididae, Salomonsen (1967) for Meliphagidae, and Rock (1919) for Lobe1ioideae . Information on range and status is taken from Berge r (1981) . H = Hawai'i, K = Kaua'i, L = Lana'i, M = Maui , Mo = Moloka'i, 0 = O'ahu; c = common, r = rare, px = presumed extinct, x = extinct

BIRD TAXON RANGE STATUS PLANTTAXON REFERENCE(S)

DREPANIDIDAE Drepanis funerea Newton Mo x Lobelioideae Perkins (1895 , (903) , Bryan (1908), Munro (1944) , Amadon (1950) D. pacifica (Gmelin) Mamo H x Lobelioideae Perkins (1903), Amadon (1950) Clermontia sp. Munro (1944) Hemignathus o. obscurus (Gmelin) 'Akialoa H px Lobelioidcae Perkins (1903) Clermontia sp. Munro (1944) H . o. lanaiensis Rothschild 'A kialoa L x Lobelioideae Perkins (1903) H. o. procerus Cabanis 'Akialoa K px Lobelioideae Perkins (1903), Munro (1944) Vestia ria coccinea (Forster) 'I'iwi M c Clermontia arborescens Spieth (1966), Berger (1981) Trematolobelia macrosta chys Berger (1981) 0 r Lobelioideae Peale (1848) unspecified islands? Lobelioideae Wilson (1890) , Perkins (1895, 1903) Viridonia v. virens (Gmelin) 'Arnak ihi H c Lobelioideae Wilson (1890), Munro (1944) V. v. chloris Cabanis 'Arnakihi 0 r Lobelioideae Wilson (1890) V. par va (Stejneger) 'Anianiau K c Lobelioideac Perkins (1903) MELIPHAGIDAE Moh o bishopi (Rothschild) '0 '6 Mo x Lobelioideae Perkins (1903), Munro (1944) M . braccatus (Cassin) '0'6 K r Lobelioideae Perkins (1903) M . nobilis (Merrem) '0'6 H x Lobelioideae Wilson (1890), Perkins (1903), Munro (1944)

1 A condensed version of this ta ble appeared in the American Journal ofBotany (Lammers and Freeman 1986). 2 In addition to M and 0 , also known from H (c), K (c), L (x), and Mo (r). 76 PACIFIC SCIENCE, Volume 41,1987

(1966)and Berger (1981)earlier observed 'I'iwi cases, no vocalizations were heard. This is the visiting flowers in this same population. first report of a non-native bird visiting the Two groups of flowering Clermontia arbo­ flowers of any of the Hawaiian lobelioids. rescens, one with two trees (a total of ten The introduction and spread of the Japa­ flowers) and the other with six trees (a total nese White-eye in the Hawaiian Islands began of 23 flowers) were observed with binoculars. in 1929 with its release on O'ahu under the The two groups were located about 50 m auspices of the Territorial Board of Agricul­ apart. Each group was observed for one hour ture and Forestry (Caum 1933). With subse­ during the afternoon of 4 July 1985. During quent releases and natural range expansion, it this period, the temperature was 15-17°C with has become the most abundant land bird in constant light precipitation. the archipelago today, occurring on all major islands from sea level to tree-line in a wide range of habitats (Berger 1981). Japanese White-eyes subsist on insects and nectar and RESULTS AND DISCUSSION are known to feed occasionally on We recorded nine visits by nectarivorous (Berger 1981). Some evidence suggests a cor­ passerine birds to flowers of Clermontia arbo­ relation between spread of the Japanese rescens. None involved the 'I' iwi, which had White-eye and decline of native passerines been reported earlier taking nectar to this (Dunmire 1962, Mountainspring and Scott population (Spieth 1966, Berger 1981). One 1985). Cox (1983) has documented that the visit involved the local race of the 'Amakihi, Japanese White-eye has become a substitute Hemignathus virens wilsoni (Rothschild). pollinator for 'Ie'ie ( arborea Although the Hawai'i and O'ahu races of Gaudich., ), a woody liana form­ 'Amakihi have previously been observed erly pollinated (in Hawai'i at least) by the feeding at lobelioid flowers (Lammers and (Corvus tropicus Kerr, Cor­ Freeman 1986), this is the first such report vidae), the Kona Grosbeak (Chloridops kona involving the race found on Lana'i, Maui, and Wilson, Drepanidinae] and the -o-n [Psit­ Moloka'i. The 'Amakihi spent about two tirostra psittacea (Gmelin), Drepanidinae]. minutes in the first group of trees, foraging in Perkins (1903) was the first to discuss in several flowers and vocalizing loudly, and detail the occurrence of ornithophily among then flew to a nearby Olapa [Cheirodendron the Hawaiian lobelioids. Because of the pro­ trigynum (Gaudich.) A. A. Heller, Araliaceae] tandrous nature of the flowers, he believed where it vigorously wiped its bill on a branch. that pollination could only be effected by The remaining eight visits were made by single drepanids and meliphagids. He speculated individuals or small groups of an introduced that once the last of these birds had disap­ passerine, the Japanese White-eye (Zosterops peared, the lobelioids would follow. In con­ japonica Temminck and Schlegel, Zoster­ trast, subsequent studies have suggested or opidae), which probed flowers for periods of demonstrated the occurrence of autogamy up to three minutes per visit. Itwas not possible in several Hawaiian lobelioids (Rock 1919, to determine whether the birds were contact­ Skottsberg 1927, Cory 1984), and these spe­ ing the staminal column and stigma or if they cies may persist despite extinction ofthe native were bearing pollen on their heads. However, avifauna. Recent studies by Cory (1984) the structure ofthe makes it likely that demonstrated nearly 100% set in selfed such contact did occur. Floral nectar samples flowers of Clermontia kakeana Meyen and obtained from these trees were found to be Cyanea angustifolia (Cham.) Hillebrand on rich in hexose sugars (Lammers and Freeman O'ahu. Japanese White-eyes were common in 1986). Such nectars are preferred by nectariv­ the vicinity of her study populations but no orous passerines (Baker and Baker 1983). The birds were ever observed visiting the flowers visits of the Japanese White-eyes were evenly in 136hr of observations. However, Young divided between the two groups oftrees. In all (1982) has shown a significant decrease in Japanese White-eyeand a Lobelioid-LAMMERS, WELLER, AND SAKAI 77 germination rate, another aspect offitness , in M .A. thesis , California State University, self-fertilized seed of two woody Afro-alpine Fullerton. species of . Cox, P. A. 1983. Extinction of the Hawaiian Any Hawaiian lobelioids that are not auto­ avifauna resulted in a change of pollinators gamous and formerly depended on native for the ieie, Freycinetia arborea. Oikos 41 : birds for pollination may benefit from the 195- 199. presence ofthe Japanese White-eye. More de­ DUNMIRE, W. W . 1962. Bird populations in tailed studies are necessary to determine the Hawaii Volcanoes National Park. 'Elepaio degree of pollen transfer effected by Japanese 22 :65 - 70. White-eyes. Even if this introduced passerine GREENWAY, J . c., Jr. 1967. Extinct and van­ is an effective pollinator, it may lead to differ­ ishing birds ofthe world, ed . 2. Dover, New ing levels of outcrossing compared to those York. resulting from visits by the native species of LAMMERS, T. G . In press. Campanulaceae. In birds. W. L. Wagner, D . R. Herbst , and S. H. Sohmer, Manual of the flowering plants of the Hawaiian Islands. Bishop Museum Press, Honolulu . ACKNOWLEDGMENTS - --, and C. E. FREEMAN. 1986. Ornith o­ We would like to express our appreciation phily among the Hawaiian Lobelioideae to the East Maui Irrigation Company, Paia, (Campanulaceae): Evidence from nectar Maui, for permission to conduct our observa­ sugar compositions. Amer.J. Bot. 73 : tions along Waikamoi Flume, and to Robert 1613-1619. Hobdy, Division of Forestry and Wildlife, MOUNTAINSPRING, S., and J. M. SCOTT. 1985. Wai luk u, Maui, for assistance in obtaining Interspecific competition among Hawaiian access to the flume. forest birds. Ecol. Monogr. 55 : 219-239. PERKINS, R . C. L. 1903. Vertebrata.Pages 365-466 in D . Sharp (ed.), Fauna Hawai­ LITERATURE CITED iensis , vol. 1, part 4. University Press, Cambridge. BAKER, H. G ., and I. BAKER. 1983. Floral PORSCH, O. 1930. K ritische quellenstudien nectar sugar constituents in relation to po l­ tiber blumenbesuch durch voge l. V. BioI. linator type . Pages 117-141, in C. E. Jones Gen. 6 : 133- 246 + pI. 28-32. and R.J. Little (eds.), Handbook ofexperi­ ROCK, J. F. 1919. A monographic study of mental pollination biology. Scientific & the Hawaiian species of the tri be Lobelioi­ Academic Ed itions, New York. deae famil y Campanulaceae. Mem. Bernice BERGER, A. J. 1981. Hawaiian birdlife, ed . 2. Pauahi Bishop Mus. 7(2) :i-xvi, 1- 395. University of Hawaii Press, Honolulu. SCOTT, J. M ., C. B. KEPLER, an d J. L. SIN­ CARLQUIST, S. 1974. Island bio logy . Co lumbia COCK. 1985. Di stribution and abundance University Press, New York. ofHawai'i's endemic land birds: Conserva­ - --. 1980. Hawaii: a natural history, ed. tion and management strategies. Pages 75­ 2. Pacific Tropical Botanical Garden, 104, in C. P. Stone and J. M . Scott (eds .), Lawai. Hawai'i's terrestrial ecosystems: Prese r­ CAUM, E. L. 1933. The exotic birds ofHawaii. vation and management. University of Occas. Pap. Bernice Pauahi Bishop M us. Hawai'i, Honolulu. 10: 1- 55. SKOTTSBERG, C. 1927. Iaktt agelser over CORY, C. 1984. Pollination bio logy of two blomningen hos Cyanea hirtella (H . Mann) species of Hawaiian Lobeliaceae (Cler­ Rock. Acta Horti Gothob. 3 :43-55. montia kakeana and Cyanea angustifolia) SPIETH, H . T. 1966. , and their presumed coevolved relationship Vestiaria coccinea (Forster), feeding on with native honeycreepers (Drepanididae). lobeliad flower s, Clermontia arborescens 78 PACIFIC SCIENCE, Volume 41, 1987

(Mann) Hillebr. Amer. Naturalist 100: YOUNG, T. P. 1982. Bird visitation, seed set, 470-473. and germination rates in two species of WHITLOCK, R. 1981. Birds at risk. Moonraker Lobelia on Mount Kenya. Ecology 63: Press, Wiltshire. 1983- 1986.