STATUS AND BEHAVlOE

Ecological observations on an endangered species: the Parrotbill, Pseudonestor xanthophrs

John H. Carothers, StephenR. Sabo and Robert B. Hansen

ESPITETHEIR REMARKABLE adaptive weeks, and the neglectof Maui's we encounteredthe parrotbillon threeoc- radiation(Raikow 1977), the natural becomesquite understandable. casions.The first time, a fleetingglimpse historiesof the Hawaiian honeycreepers wascaught of a singingmale which flew (Drepanidinae)are poorlyknown. With- EFIRST BECAME acquainted withthe by us. Perhapsbecause of its massive in thisfringillid subfamily are birdswith Maui Parrotbill as members of the bill. thebird appearedto dragits headin foragingbehaviors similar to , U.S. Fish and Wildlife Service's Hawai- flight. In our next encounter,we ob- warblers,nectar feeders, woodpeckers, ian ForestBird Survey.In May 1980, we servedits typical foraging method. When creepers,and parrots: they thereby fill a traveled to a remote area in the Ko'olau perchedon a branch,a feedingparrotbill diversityof nichesthat in continental ForestReserve on the northslope of Ha- reachesforward with its head, grasping areas requiresalmost as many orders leakala volcano of east Maui. Here the the branchin its bill. This may be per- (Mueller-Domboiset al. 1981). Despite Maui Parrotbill and the still rarer Nuku- formedin an upright,vertical, or upside- recent work on fossil remnants of the pu'u (Hemignathuslucidus affinis) were down posture.Then. while pulling its archipelago'savifauna (Olson and Wet- seenin 1973 by a researchteam conduct- head back, it uses the tip of its upper more 1976, Olson and James 1982), ing the first floral and faunal investiga- mandibleto scratchor peel off and much of the evolutionarystory of the tion of this area, the team that discovered outer twig layers. A feeding may birds will never be told. At the turn of the thePo'o Uli. Very few expeditionsin this perform several "peeling" motions in century,32 speciesof native area (Banko 1968, Shallenbergerpers. quick succession,making it difficult at lived on the main islands--13 are now comm.,and Scottpers. comm.) have re- first to tell whether the bill is used when extinct. Of the 19 remainingspecies, 13 portedsightings of a parrotbill.Prior to the head is reached forward or pulled are on theendangered species list (Shal- theseaccounts, the only other recordfor back. lenberger1981). Althoughsome species this centurywas in December 1950 by The extraordinarybill shape of this still survivein numbers,many insular Richards and Baldwin (1953). bird intriguedus, and as part of a docu- populationsare now extinct, such as the On this first expeditioninto the forest, mentarystudy, we collecteddata on the Akohekohe (Palmeria dolei) on Molo- kai, or the l'iwi (Vestiaria coccinea)and Amakihi (Hemignathusvirens) on Lanai. Other islandpopulations are endangered (e.g., the Akepa. Loxopscoccinea, on Maul and ). Field studies on Maul rainforest birds have in particularsuffered long neglect. In 1973a new speciesof drepanididwas discoveredon Maul, the Po'o Uli (Me- lamprosopsphaeosoma) (Casey and Ja- cobi 1974), and in 1981 Bishops'sO'o (Moho bishopi) was discoveredin the same montane rainforest (Sabo 1982). The montane rainforest of east Maul is tracklessand forbidingly remote. A long strenuous hike across a cinder desert is requiredto reachthe remnantforest that still harborsan invitinglyrich fractionof the native avifauna. There the terrain is typicallyhazardous, with densevegeta- tion concealingmany gorges,sheer ra- vines,and deep stream cuts. Add to these privationsthe frequentrains depositing 300 inchesannually that can continue for Fig. 1. Maui Parrotbill.Photo/John H. Carothers.

820 AmericanBirds, Scplember-October1983 height, species,substrate, and feed- whistled "doo-weet", a similar Museumof VertebrateZoology at U C lng methodfor 127 Main Parrotbillprey "pweet", anda shortrepeated chip. The Berkeleyfor financial supportmaking capturesduring subsequentexpeditions first of theseis also given by the Nuku- thiswork possible.Personnel of the U S In 1980 and 1981. The parrotbillprefers pu'uand the much more common Akohe- Fishand Wildlife Service(C. Keplerand to foragefor insectson deadbranches or kohe, and a similar call is given by the M. Scott), and of Haleakala National twigson live (65% of all captures). commonI'iwi and Amakihi. The repeti- Park (C. Crivellone, R. Fox, A. Me- As expected,it feedsmost often (51%) tiouschip is virtuallyidentical to contact dieros,L. Loop, B. Cooper,R. Nagata), on the dominant forest tree, the Ohia notes producedby the abundantMaui andthe Kepler family providedvital sup- (Metrosideroscollina), but thereare rec- Creeper(Paroreomyza montana). Inter- port,and we singtheir praise. H. Greene ordsof itsforaging on 12 otherplant spe- estingly, many of our Maui Parrotbill kindly reviewedthe manuscript. cies. It foragesin the foliage column, sightingswere of individualsforaging REFERENCES usuallyfrom 1 to 11 metershigh, with with smallgroups of creepers,with both maleson the averagefeeding higher than speciesapparently calling back and forth BANKO, W.E., 1968. Rediscoveryof Main among themselves.Both species are females.Gleans for insectprey off a vari- Nukupuu,Hemignathus lucidus affinus, ety of substratesconstitute 17% of all similarlysized (11-14cm), with females andsighting of Maui ParrotbillPseudones- preycaptures. It alsooccasionally probes olive drab above and yellow-green be- tor xanthophrys,Kipahulu Valley, Main, In flowersand leaf axils (7%). Most com- low. Males of both speciesin breeding Hawaii. Condor 70:265-266. mon is excavation on a branch or trunk plumageare olive drab aboveand bright CASEY, T.L.C., and J.D. JACOBI, 1974 A (65%); thebird maybegin by insertingits yellow below. The male Maui Parrotbill new genusand speciesof bird from the island of Maui, Hawaii (Passeriformes alsohas a yellowsuperciliary streak and a uppermandible in a barkdeformity, peel Drepanididae).Occ. Pap. Bernice P up severalinches of barkby usingits bill dark line through the eye (see photo). BishopMus. 24:215-266. sideways,and finally dig in with its bill Althoughoften seenwith creepers,par- MUELLER-DOMBOIS,D., K.W. BRIDGES, tip when the prey is accessible.Even rotbills were formerly also associated andH.L. CARSON, 1981.Island ecosys- moreamazing maneuvers occur when the with Nukupu'us when both were more tems:Biological organization of selected bird locatesa borer larva in a twig (12% abundant(Perkins 1903). In over 120 ob- Hawaiiancommunities. US/1BP Synthest, Series 15. HutchinsonRoss Publ Co, of preycaptures). Here the bird takesthe servationsof the parrotbill,we neversaw Stroudsburg,PA. twig betweenits mandiblesand splitsit; thesetwo speciestogether. OLSON, S.L., andH.F. JAMES, 1982. Fos- If the twig is stubborn,the bird may at- Perkins (1903) frequently found the sil birds from the Hawaiian Islands: evi- temptto shearit in half usingits head as a Maui Parrotbillfeeding in Koa trees,and dencefor wholesaleextinction by manbe- wrench. Should the larva retreat down its we saw the bird probing rust-infected fore western contact. Science 217:633- twig burrow, the bird splits the twig Koa leaves on several occasions. Unfor- 635. again.Foraging in thismanner, the Maui tunately,most of the drier Koa forest,a --and A. WETMORE, 1976. Preliminary Parrotbill resembles a leathered can- favored that at one time covered diagnosisof twoextraordinary new genera of birdsfrom Pleistocenedeposits in the opener.In bothsplitting and excavating, muchof thewestern slopes of Haleakala, Hawaiian Islands. Proc. Biol. Soc. Wash the parrotbilluses its tongueto extract has been almost entirely destroyed 89:247-257. prey. throughlumbering and especially grazing PERKINS, R.L.C., 1903.Vertebrata (Aves) domesticcattle. Feral pigsare also a very In D. Sharp(ed.) FaunaHawaiiensis. Vol ALEPARROTBILLS arelarger than fe- seriousproblem within the rainforest, 1. TheUniversity Press, Cambridge, Eng- males, particularlyin bill length. land. causingpersistent erosion and often se- Males appearto excavatedeeper into the RAIKOW, R.J., 1977. The originand evolu- vere understorydamage. In additionto substratethan females. Moreover, males tion of the Hawaiianhoneycreepers (Dre- , other factors detri- feed more often on large trees than fe- panididae).Living Bird 15:95-117. mental to the Maui Parrotbill include the RICHARDS, L.P. and P.H. BALDWIN, males, while females feed more often on introducedPolynesian rat, mongooses, 1953 Recent records of some Hawaiian shrubs,perhaps because the dominant andferal cats.The presenceof avian ma- honeycreepers.Condor 55:221-222. Ohla and Koa () trees have laria vectorshave also beensuggested as SABO,S.R., 1981.The. rediscovery of Bish- harder wood than shrubs. Sexual dimor- op's O'o on Maui. Elepaio42:69-70. a majorfactor in the extinctionof many phismis well knownin somegroups, and SHALLENBERGER, R.J., 1981. Hawaii's Hawaiianendemic birds (Warner 1968). in woodpeckers,for example,bill differ- birds.3rd ed. HawaiianAudubon Society, Our observations indicate that the Maui Honolulu. encesalso relate to foragingstyles (Se- Parrotbill, although very rare, is more SELANDER, R.K., 1966. Sexual dimor- lander 1966). It is possiblethat this di- commonthan previouslybelieved. Re- phismand differentialniche utilizationin morphismevolved to reduceintra- and birds. Condor 68:113-151. plantingnative Koa forestin someareas interspecificcompetition, although now- WARNER, R.E., 1968. The role of intro- to replaceexotic treesand pastureland, adaysthe parrotbill and its potential com- duced diseases in the extinction of the en- along with feral management, petitor, the Nukupu'u, are both so rare demic Hawaiian avifauna. Condor mayaid the survivalof thisendangered, 70:101-120. that theremust be little presentadvan- fascinatingbird. tage. --Dept. of Zoology and Mus. of Vert We heard males singing from May ACKNOWLEDGMENTS Zoology,Univ. of Califorma, throughAugust. The song is quite dis- Berkeley,CA 94720 (Carothers), tinct, and comprisesabout seventrilled EWISH to thank the Frank M. Chap- Dept. of Statistics, Oregon State "tuey" notesthat typicallydescend, al- man Fund of the American Muse- Univ.Corvallis, OR 97331 (Sabo)and thoughthere may be onlya slightchange umof NaturalHistory, Sigma Xi (Grant- The Nature Conservancy,Creighton In pitch.Both males and females produce in-aidof Research),the Departmentof Ranch Preserve, 3450 Ave. 144, threetypes of call notes,a brief upslurred Zoologyand the Carl Koford Fundof the Corcoran, CA 93212 (Hansen)

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