Pacific Science (1999), vol. 53, no. 4: 319-340 © 1999 by University of Hawai'i Press. All rights reserved New Behavioral, Ecological, and Biogeographic Data on the Avifauna of Rennell, Solomon Islands 1 CHRISTOPHER E. FILARDI,2 CATHERINE E. SMITH, 2 ANDREW W. KRATTER, 3 DAVID W. STEADMAN,3.5 AND H. PRICE WEBB4 ABSTRACT: During an expedition to Rennell, Solomon Islands, from 20 to 30 June 1997, we collected specimen and observational data that add to our under­ standing of this island's unique avifauna. We observed three species previously unrecorded on Rennell: a putative caprimulgid species, the Tree Martin (Hirun­ do nigricans), and the Black-faced Cuckoo-shrike (Coracina novaehollandiae), suggesting that further research will add to the known Rennell avifauna. In combination with previous work, our specimen data suggest that many Rennel­ lese land birds have prolonged breeding seasons typical ofthose ofbirds oflow­ land tropical regions. Our observations indicate that two species, the Great Cormorant (Phalacrocorax carbo) and the Singing Starling (Aplonis cantor­ oides), have colonized Rennell and increased in abundance over the past several decades. Reported initially as vagrants, the population establishment and in­ creases of these two species portend the importance of vagrant species on islands subjected to increased human disturbance. RENNELL ISLAND LIES 168 km south of the nell's avifauna is depauperate, having about main chain of the Solomon Islands (Figure 50% of the species richness of a comparably 2 1). The avifauna of this large (676 km ) up­ sized island in the main chain of the Solo­ lifted coralline limestone island is indisput­ mons (Diamond and Mayr 1976). Systematic ably distinct. Of 37 breeding land and fresh­ affinities suggest that dispersal of species to water bird species, five species and nine Rennell may have occurred directly from subspecies are endemic, and six additional Vanuatu, New Caledonia, and Australia in subspecies are endemic to Rennell and addition to the main chain of the Solomons nearby Bellona (a smaller raised limestone (Diamond 1984). island 24 km northwest of Rennell). Ren- Rennell's birds are known largely from analysis of external characters from study skins plus observations duri~g infrequent re­ search expeditions. Initial scientific explora­ 1 Financial support came from the University of Flor­ tion by Stanley and Hogbin in 1927 was fol­ ida Division of Sponsored Research (to D.W.S.), lowed with two visits by the Whitney South National Science Foundation grant EAR-9714819 (to D.W.S.), the Ornithology Endowment at the University Seas Expedition in 1928 and 1930 (Mayr of Washington Burke Museum (to C.E.F., C.E.S.), the 1931, Mayr and Hamlin 1931), additional University of Washington Department of Zoology work by Bradley and Wolff (1956), and more (C.E.F., C.E.S.), an Eddy Fellowship (C.E.F.), and an recently Wolff (1973) and Diamond (1984). NSF Predoctoral Fellowship (C.E.S.). Manuscript ac­ Most expeditions to Rennell have occurred cepted 1 February 1999. 2 Burke Museum and Department of Zoology, Uni­ frorn August to November, with one trip in versity of Washington, Box 353010, Seattle, Washington May 1930, and four days in June-July 1933. 98195-3010. Unfortunately, specimens collected in the 3 Florida Museum of Natural History, University of 1920s through 1950s typically lack the exten­ Florida, P.O. Box 117800, Gainesville, Florida 32611. 42048 White Oak Circle, Kennesaw, Georgia 30144. sive data that give modern specimens so 5 Corresponding author (telephone, 352-392-6571; fax, much value, such as weight, soft part colors, 352-846-0287; E-mail, [email protected]). molt, gonad size and condition (to determine 319 320 PACIFIC SCIENCE, Volume 53, October 1999 ,~.:.;\ .r if X "" Ontong Java Atoll ~~.~:~~~~: :::'::-':'0, \'l}-i\\Ver,'a­ -..l~'bq:~., ......\•.1 "' ro?;\O\'b ~Ia Lavella Arnavon Is. (same scale) 0 Mbava::-.w:~"IItJ°JOmbangara 6 S ~Dai iJR~~~fador ~ Ranongga5\'\} [i0. New Georgia vonavo~ Simbo# Sikaiana .; .. KOhingg;:J . NEW GEORGIA RendOV~ nVan9UnU FLORIDA ~ 'V-o. ISLANDS ,.. ~ GROUP Telepare Nggalokae ~p ~~~\e i. ~~. ! G ~~~UYU Mborokua Sav8 ~Nggela ~ I RUSSELL Pile SOLOMON ISLANDS ISLANDS o 100 200 300 ! I I I KM ~ Bellona ~nell Sanla ?Ana 12°S t···. "·f:. IndIspensable Reels :.:,~ :'~1'~ ~ame scale) .. ~:~~,: 1600 E \\ FIGURE 1. The Solomon Islands. breeding phenology), bursa and skull ossifi­ pare with those of Diamond and others, cation (to determine age of specimens), and higWight the most striking differences and stomach contents. In addition, tissue preser­ their significance, and comment on changes vation (for molecular analyses) was not a in Rennell's avifauna over the past half common practice until this decade, and only century. one previous expedition to Rennell (M. C. LeCroy and H. P. Webb in June 1995) pre­ Study Area and Methods served tissue samples. Because of these pro­ nounced gaps, the knowledge about Rennell On 20 June 1997, we flew from Gua­ Island birds was enhanced considerably by dalcanal to Hatagua Airstrip at Tinggoa Vil­ our specimen data and field observations lage, near the west end of Rennell (Figure 2), during 20-30 June 1997. arriving at 0830 hours. We spent 24 hr near The most recent and complete treatment the airstrip observing birds and passed the of the Rennellese avifauna is by Diamond night at Mendana Resthouse (MR) at the (1984), based on fieldwork during 5-13 Oc­ west end of the airstrip. On 21 June we de­ tober 1976. Although his observations are parted for Lake Te Nggano, the largest lake extensive, Diamond collected no specimens. in the South Pacific. The 8-hr tractor journey To avoid repetition, we provide only a cur­ included frequent stops, when we made ad­ sory treatment of topics covered more thor­ ditional observations. We arrived at the lake oughly by Diamond. Following the species several hours after dark. A 45-min canoe ride accounts, we address how our results com- took us to the Tahamatangi Resthouse (TR), New Data on the Avifauna of Rennell-FILARDI ET AL. 321 11° 40' S RENNELL o......2 4 6 8 kilometers 0123456 miles FIGURE 2. Rennell Island, showing localities mentioned in text. near Hutuna Village on the west shore of the last two days, when no substantial precipita­ lake. TR served as our base from 22 to 28 tion occurred. June. Most of our observations and specimen Much of the fruiting and flowering was collections were within a 2-km radius of TR confined to various epiphytes, understory (see locality specifics below). We made day plants, scattered trees (e.g., Ficus spp., Va­ trips to mature forest and Tuhungganggo vaea sp., Cocos nucifera), or early succes­ Beach on 24-26 June. On 28 June we de­ sional and edge species, such as Hibiscus ti­ parted TR, crossed the lake again, and re­ liaceus, Macaranga harveyana, and Pipturus turned by tractor to the airstrip. Again we argenteus. Most of the large canopy trees, stayed at MR, observing birds along the trail such as Canarium, Myristica, Callophyllum, west of the airstrip on the afternoon of 28 Homalium, and Terminalia, were not in fruit June and morning of 29 June. We departed or flower. for Guadalcanal at midday on 29 June. We set up three mist-net lines. Five nets Mornings at Lake Te Nggano generally were placed along a transect through sec­ began with hazy to partly cloudy skies and ondary forests of various ages, including two strong winds off the lake just south of east at nets in recently abandoned « 5 yr) garden ca. 25 km/hr. Daytime temperatures reached plots and three nets in denser, older (l0­ ca. 28°C. Mternoons featured rain squalls off 20 yr) second growth. The canopy was less the lake that on several occasions coalesced than 10m tall in both habitats. Three nets into heavy rains late in the day. Winds were set up in more mature forest I km to­ maintained a heavy chop on the lake, which ward Hutuna from TR. These two lines op­ prevented canoe travel to the islets that har­ erated from 22 to 27 June. Three additional bor roosts of aquatic birds. The winds settled nets were set up from 25 to 26 June in tall, and skies became more overcast during our mature forest ca. 2 km from Tuhungganggo 322 PACIFIC SCIENCE, Volume 53, October 1999 Beach. Net captures were supplemented with morning of 21 June, late afternoon 28 June, collection of birds via hunting by Rennellese and morning of 29 June. We made observa­ Mart Taieha. The specimens (skins, skel­ tions from the airfield, the resthouse and vi­ etons) are housed at the Florida Museum of cinity, and along 1.5 km of road heading Natural History (UF), the University of west from the airstrip through active and Washington Burke Museum (UWBM), and abandoned gardens, secondary forests, and the Solomon Islands National Museum. edges of mature forests. Stomach contents from collected speci­ We did no standardized censusing of mens, preserved in isopropyl alcohol, are birds. Measures of relative abundance reflect housed at UFo Stomach contents were iden­ incidental encounter rates of a species and tified by A.W.K. using a light microscope. were assigned according to the following cri­ Heart, liver, and muscle tissue were taken teria: (1) rare, encountered once or twice at a from all specimens deposited at UWBM and locality pooling all observers over all days; most specimens deposited at UFo Tissues (2) uncommon, encountered daily or almost were minced under sterile conditions and put daily at a locality, pooling all observers over in kryo tubes with lysis buffer. Field ob­ all days (encounter rate variable); (3) com­ servations were tabulated daily. Species ac­ mon, encountered regularly by all observers counts based on cumulative notes and ob­ over all days at a locality; (4) abundant, servations by all authors were compiled unavoidable fixtures of a given habitat or immediately after leaving Rennell.