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Home , Banks Islands, Efate, Emae, Erromango, Espiritu Santo, Gaua

THE JOURNAL OF RAPTOR RESEARCH A QUARTERLY PUBLICATION OF THE RAPTOR RESEARCH FOUNDATION, INC.

VOL. 31 DECEMBER 1997 NO. 4 j RaptorRes. 31 (4):303-307 ¸ 1997 The Raptor ResearchFoundation, Inc.

OBSERVATIONS OF RAPTORS IN THE REPUBLIC OF

WADE L. EAKLE 1 WorldWorking Group on Birdsof Preyand Owls,Wangenheimstr. 32 D-14193 Berlin,Germany

ABSTRACT.•Roadand trailsidesurveys were conductedin the Republicof Vanuatu,formerly known as the in the SouthwestPacific, to determine relative abundanceof raptors.Three diurnal and one nocturnalspecies were observedduring 74 hr of observationover 594 km surveyed.Swamp Harriers ( Circusapproximans approximans) were mostfrequent and found on all islandssurveyed includ- ing (N = 6), EspirituSanto (N-- 31), (N = 11) and Tanna (N = 19). PeregrineFalcons (Falcoperegrinus nesiotes) were observedon Gaua (N = 2) and Tanna (N-- 1), while Brown Goshawks (Acdpiterfasdatusviligax, N = 2) and Barn Owls (Tyto alba interposita,N = 2) were observedon Tanna and , respectively.Observations of SwampHarriers on Gaua and Brown Goshawkson Tanna are the first reported for these specieson these islands. Indices of relative abundance were calculatedfor each speciesbased on the number of individualsobserved per km traveled. K•Y Worn)s: BrownGoshawk; Accipiter fasciatus viligax; raptor roadside survey; relative abundance;, Swamp Harri• Circus approximans approximans; Vanuatu.

Observacitnesde rapace en la Republica de Vanuatu R•suM}•N.--Estudiosde caminosy callesfueron conducidaden la Republicade Vanuatu antesconocido como Nuevo Hebrides en el Pacifico del Sud-oeste,para determinar la abundancia relativamentede rapace.Tres especiedel dia y uno de la nochefueron observadosdurante 74 hr en una region de 594 km. Circusapproximans approximans fueron masfrecuente, y locolizadosen todaslas islas inspeccionadas incluyendoEfate (N = 6), EspirituSanto (N = 31), Gaua (N = 11), y Tanna (N = 19). Falcopereginus nesiotesfueron observadosen Gaua (N = 2) y Tanna (N = 1), fueron observadosen Tanna y Espiritu Santo, respectivamente.Observacitnes de aguiluchosen Gaua y Accipiterfasdatusviligax en Tanna son las primerasespecie reportadas en estasislas. Indice de abundanciarelativa fueron calculadaspara cada especiebasado en numero de individualesobservados por km caminados. [Traduccitn de Rafil De La Garza,Jr.]

Tropical rainforestsare perhapsthe mostbiolog- habitats, population numbers and trends, and en- icallyrich terrestrialhabitats in the world.Thiollay vironmental factors limiting their numbers. Burn- (1994)estimated that over 46% 'of the world's pres- ham and Cade (1995) recently suggestedthat ently recognized falconiforms are tropical forest more attention should be focusedon speciesthat species.Tropical forest raptors, including strigi- are little known and needing study and in geo- forms, are also much less known than Nearctic and graphical"hotspots," because those species and lo- Palearcticspecies, and in need of further studyto cations are most likely to be, or are soon to be- better understand their basic biological and eco- come, jeopardized through continued human en- logical requirements,including densityin certain croachment and development. Though not recognizedas a geographical"hot- 1Present address:U.S. Army Corps of Engineers, spot" for its high biodiversitylike the nearby is- Division, Regulatory Program Office, 333 lands of and , the Re- Market Street, San Francisco, CA 94105-2197 U.S.A. public of Vanuatu is an important faunal cross-

303 304 E•CLE VoI•. 31, No. 4 roads where the main streams of colonization of Standardized road and trailside counts were conducted SouthwestPacific meet (Bregulla 1992). This on the islandsof Efate, Espiritu Santo, Gaua and Tanna using a car and on foot from 19 October-7 November nation of large and small islandshas received little 1996 (Fig. 1). Three to four observerswalking and trav- attention from biologistsdue in part to its remote eling together located and identified raptors on both location. Most of the residentbirds are thought to sidesof roads or trails during thesecounts, and recorded have been derived from , New Guinea or data on speciesand number observed,habitat type and . Residentraptors include the Brown or Austra- activity(Thiollay 1989). Driving speedswere variable, but roadwayconditions always limited speedsto •40 km/hr. lian Goshawk (Accipiterfasdatus vigilax), Swamp When raptors were observed,the vehicle was stopped (Circus approximansapproximans), Pere- momentarilyto identify the birds. Periodicstops were grine Falcon (Falcoperegrinus nesiotes) and Barn alsomade to scanfor distantraptors in open habitatsor Owl (Tytoalba interposita and T. a. lulu). The Brah- over the forest canopywhenever conditions allowed. The location of each observationwas plotted on 1:50 000 or miny Kite (Haliastur indusflavirostris) occurs as an 1:100000 scale maps of the islands,and the d•te•'•hd occasionalvagrant from the neighboring Solomon time of each sightingnoted. Surveytimes ranged from Islands(Wattel 1973,Weick 1980, Bregulla1992). 0500-1900 H. Weatherconditions were variableduring During a related studyof Vanuatu'slargest and the surveyperiod, but mostlywithout any precipitation. Some studies have indicated that roadside and trailside most accessible islands to determine if Sanford's counts can give biased estimatesof raptor densitiesand Sea Eagle (Haliaeetussanfordi), thought to be en- habitat associations. However, road counts can be useful demic in the , occurs in the ar- and appropriate when large areasneed to be sampled chipelago as a resident or vagrant species,I also and monitored (Fuller and Mosher 1987). Use of road- soughtto determine the distribution of the islands' waysand trails on Vanuatuwas the only feasiblemeans of satisfyingthe studyobjectives. birds of prey, and estimatetheir observedrelative I used the method developedby Woffinden and Mur- abundance. Here, I used numbers of individuals phy (1977) to calculatean index of observedrelative observedper km traveled,and numbersseen per abundancefor each raptor speciessighted: hr of observation, to estimate relative abundance Index = [ (Total number of a speciesobsepeed) during a roadside and trailside survey.This may -' (Total km traveled)] X 1000 not have been done previouslyfor the islands.

STUDY AREA AND METHODS RESULTS AND DISCUSSION Located between the equator and the Tropic of Cap- Nearly 600 km were traveledand 74 hr of obser- ricorn (13-23øS,166-173øE), the Republicof Vanuatuis vation time logged (Table 1), givingan averageof a chain of about 100 ash and coral uplifted islandsand islets. They were formerly known as the New Hebrides 1.0 raptors sighted per hr of observationtime, or until 1980 when independencewas gained from the con- 0.12 individualssighted per km (8.0 km traveled dominium governmentsof France and the United King- per sighted). dom. The Y-shapedarchipelago of mainly smallvolcanic Swamp Harriers were most common and ac- islandsoccurs in one of the mostgeologically active areas in the world,and ispart of a continuousisland arc system countedfor 90% of the raptorssighted (Table 2). stretching from and the Solomon Is- Bregulla (1992) suggestedthe SwampHarrier was lands to Fiji and . The largestisland is EspirituSan- the largest raptor in Vanuatu, and found on most to with a surfacearea of 3900 km2. Other major islands islands,except Gaua, , Mere Lava and include Efate (915 km9), Gaua or Santa Maria in the . Also known as the Pacific Marsh Harri- group (310 km9) and Tanna (572 km9) er, Areadon et al. (1988), Olsen (1995) and Clarke whichare mountainousand extremelyrugged. The high- est peak in Vanuatuis Mt. Tabwemasanaon EspirituSan- (1995, 1996) suggested,and others (Grossmanand to at 1879 m (Fig. 1; Bregulla1992). Hamlet 1964, Brown and Areadon 1968, Watson Vanuatuhas a wet, tropicalclimate in the north grad- 1977,Weick 1980, Cupper and Cupper1981) ear- ually changingto subtropicalin the south,and largely lier treated, the SwampHarrier and three other exposed to prevailing southwesterlywinds. Evergreen rainforestcovers about 75% of the country.Three major Circusspecies as a complex, conspecificwith the plant communitiesare readilyrecognized on the larger widely distributed Western (C. aeru- mountainous islands,including evergreen tropical rain- ginosus)of , North and the Middle forest on the lowland,warm, wet, windwardslopes; semi- East.My observationsof SwampHarriers (N = 11) deciduousforest and fire-inducedsavannahs and grass- on Gaua suggestthe speciesmay be extending its lands on lowland,warm, drier, leewardslopes; and ever- green forest on upland and summit areas with cooler, range in the archipelagoto previouslyunoccupied wetter and more humid climatic conditions (Bregulla islands.Alternatively, Swamp Harriers may have 1992, Harcombe and O'Byrne 1995). been present,but simplyunobserved during pre- D]•C]•MB]•]• 1997 R•TO]•S IN V•a,•U^TU 305

REPUBLIC OF VANUATU 0 50 1 O0

[•TORRESISLANDS KILOMETERS LAKE • LET•.•/ •0 • GAUA •:• MOTALAVA 0 10 20 30

VANUALAVA•3(3 KILOMETERS BANKS ISLANDS

E•A'•E EFATE KILOMETERS 0 10 20 30

KILOMETERS ERROMANO0 '• COR A L i...... •I;,'• \VANUATUREPUBLIC ßOF

.:. TANNA 0 10 20 50 AUSTRALIA/ PA C IF IC 0C EA N • KILOMETERS • j' TASEAS M A N '•EWZEALAND

Figure 1. Raptorsurvey routes in the Republicof Vanuatu,19 October-7November 1996. 306 EAKLE VOL. 31, NO. 4

Table 1. Islands surveyed,distances traveled, and du- Table 2. Frequencyof raptor sightingsand observedrel- ration of raptor surveysconducted in Vanuatu, October- ative abundanceindices of raptorssighted during surveys November 1996. in Vanuatu, October-November 1996.

NUMBER km AND OBSERVA- TRAVELED INDEX OF TYPE OF TION DISTANCE NUMBER PER RELATIVE SURVEY TIME TRAVELED OB- INDMD- ABUN- ISLAND (CAR/FOOT) (hr) (km) SPECIES SERVED UAL DANCE a Efate 1 7.0 146 2 4.5 10 ( Circusapproximans Esplritu Santo 5 14.5 302 approximans) 67 8.9 112.8 5 11.5 26 Peregrine Falcon Gaua (Santa Maria) ------(Falcoperegrinus 4 16.0 35 nesiotes) 3 198.0 5.1 Tanna 1 2.5 37 Brown Goshawk 4 18.0 38 (A cdpiterfasdatus Total 22 74.0 594 viligax) 2 297.0 3.4 Barn Owl ( Tytoalba interposita) 2 297.0 3.4 aAnalysis of relative abundance after Woffinden and Murphy vious surveysof the island. However, I find this ex- (1977). planation lesslikely given SwampHarriers tend to spend most of the day on the wing, usually over open habitatsbut also frequently over forest, and on northeastern Espiritu Santo near should have been readily observedif present (Bre- would probably be assignedto the former based gulla 1992). Elsewherein the South Pacific, C. a. on the location of these sightings. approximansoccurs on Wallis Island, the LoyaltyIs- Brown or Australian Goshawkswere sighted on lands, New Caledonia, Fiji, Tonga, the SocietyIs- the island of Tanna (N-- 2; Table 2), and are ob- lands, , Chatham and Kermadec Islands servationsequally significant to the Swamp Harri- (Brown and Amadon 1968, Hollands 1984). ers seen on Gaua. Wattel (1973), Weick (1980) and Peregrine Falconswere observed on the islands Bregulla (1992) describedA. f vigilaxas similarin of Gaua (N = 2) and Tanna (N = 1), while Barn plumage to the nominate subspeciesA. f fasciatus Owls where observed on Espiritu Santo (N = 2; of Australia, but smaller in size and found on New Table 2). Bregulla (1992) suggestedboth species Caledonia and the Loyalty Islands. The only pre- were found on most islands of Vanuatu. Several au- vious definite records for the Brown Goshawk in thors including Brown and Amadon (1968), Weick Vanuatu are from the island of Aneityum, south of (1980), White and Boyce (1988) and Ratcliffe Tanna, where it was not numerous (Bregulla (1993) describedE p. nesioteson the islandsof Va- 1992). My observationsof two Brown Goshawksin nuatu, the LoyaltyIslands, New Caledoniaand Fiji. lowland wooded habitat near the village of White In addition to the island of Tanna, Peregrine Fal- Sands,north of Mt. Yasur (361 m), suggestthe spe- cons have been observed breeding on the islands cies may also be extending its range in the archi- of , , , Vete Manung, Efate pelago. However, since the Brown Goshawk fre- and during aerial surveysconducted from quents a variety of wooded habitatsin lowlandsand 1993-95 (C.M. White, pers. comm.). mountains, including forest edges,wooded grass- Bunn et al. (1982), Bregulla (1992) and Taylor lands and secondarygrowth, it could have been (1994) identified two subspeciesof Barn Owl in present yet easilyoverlooked during previous sur- Vanuatu, T. a. interpositaon the northern islands veys on Tanna. (and the [Solomon Islands]) Wattel (1973) suggestedVanuatu was colonized and T. a. lulu on the southern islands of Vanuatu in the distant past by Brown Goshawksfrom New (Erromango, Tanna and Aneityum), the LoyaltyIs- Caledonia, with the successof A. fasdatus as an is- lands, New Caledonia, Fiji, Tonga, Samoa and the land colonistfurther emphasizedby its occurrence SocietyIslands. My observationsof two Barn Owls on many small islands to the north and northeast DECEMBER 1997 RAPTORS IN VANUATU 307 of Australia. Geographicalvariation in the size of FULLER,M.R. ANDJ.A. MOSHER.1987. Raptor survey the Brown Goshawkprovides a good example of techniques.Pages 37-65 in B.A. Giron Pendleton, "Bergmann's rule," such that all tropical subspe- B.A. Milsap, ILW. Cline and D.M. Bird [EDS.],Raptor cies are smaller than the temperate Australian and management techniques manual. Natl. Wildl. Fed., Washington,DC U.S.A. nominatesubspecies, A. f fasciatus(Pianka 1978). GROSSMAN,M.L. ANDJ. HAMLET. 1964. Birds of prey of Sanford's Sea-Eagleswere not observed on the the world. Bonanza Books, New York, NY U.S.A. islandssurveyed. However, future investigationsin HARCOMBE,D. ANDD. O'BYRNE.1995. Vanuatu: a Lonely the , the northwestern most island Planet travel survivalkit. 2nd ed. Lonely Planet Pub- group in the archipelago, could prove fruitful. lications, Hawthorn, Victoria, Australia. These islands are less than 452 km southeast of San HOLLANDS,D. 1984. Eagles, hawks and falcons of Aus- Cristobal in the Solomon Islands where Sanford's tralia. Thomas Nelson, Melbourne, Victoria, Australia. Sea-Eaglehas been observed in the past (Brown OLSEN,P.D. 1995. Australian birds of prey: the biology and Amadon 1968). and ecologyof raptors.John Hopkins Univ. Press,Bal- timore, MD U.S.A. ACKNOWLEDGMENTS PIANI•, E.R. 1978. Evolutionaryecology. 2nd ed. Harper L.A. Barekman,G. Chatfield and T.L. Harrell provided & Row Publishers, Inc., New York, NY U.S.A. invaluable assistancein the field. G. Russellof Butterfly RATCLIFFE,D. 1993. The PeregrineFalcon. 2nd ed. T. & Tours provided logisticalsupport on Espiritu Santo and A.D. Poyser,Ltd., London, UIL made arrangementsfor local support on Gaua. B.D. Wil- TAYLOR,I. 1994. Barn Owls: predator-preyrelationships kins and D. Iou provided guide serviceson Gaua and and conservation.Cambridge Univ. Press,Cambridge, Tanna, respectively.D.IL Garcelon, R. O'Keefe, R. Wat- UIL son, C.M. White and two anonymousreferees provided THIOLLAY,J.M. 1989. Censusingof diurnal raptors in a critical commentson earlier draftsof the manuscript.PJ. Scheetzprepared the figure of the studyarea, and B.-U. primary rain forest:comparative methods and species Meyburg provided study endorsementfrom the World detectability.J. RaptorRes. 23:72-84. Working Group on Birds of Prey and Owls. 1994. A world review of tropical forest raptors: current trends, research objectivesand conservation LITERATURE CITED strategy.Pages 231-239 in B.-U. Meyburg and R.D. AMADON,D., j. BULL,J.T. MARSHALLAND B.E I•NG. 1988. Chancellor, lEDS.], Raptor conservationtoday. World Hawks and owls of the world: a distributional and tax- Working Group on Birds of Prey and Owls, Berlin, onomic list. Proc. West.Found. Verte& Zool. 3:295-357. Germany. BREGULLA,H.L. 1992. Birds of Vanuatu. Anthony Nel- WATSON,D. 1977. The . T. & A.D. Poyser, son, Oswesty,Shropshire, UIL Berkhamsted, Hertfordshire, UIL BROWN,L. ANDD. AMADON.1968. Eagles,hawks and fal- WATTEL,J. 1973. Geographicaldifferentiation in the ge- consof the world. Country Life Books,Feltham, Mid- nus Accipit• Nuttall Ornithological Club, Cambridge, dlesex, UIL MA U.S.A. BUNN, D.S., A.B. WARBURTONAND R.D.S. WILSON. 1982. WEICK,F. 1980. Birds of prey of the world. Verlag Paul The Barn Owl. Buteo Books, Vermillion, SD U.S.A. Parey,Hamburg and Berlin, Germany. BURNHAM,W.A. ANDTJ. CAr•E.1995. Raptor populations: WHITE, C.M. AND D.A. BO¾CE,JR. 1988. An overview of the basis for their management. Pages 115-130 in Peregrine Falcon subspecies.Pages 789-810 in TJ. Trans. 60th No. Am. Wildl. & Natur. Resour. Conf., Cade, J.H. Enderson, C.G. Thelander and C.M. Wildl. Manage. Institute, Washington,DC U.S.A. White, [EDS.], Peregrine Falcon populations: their CI•tRKE,R. 1995. The Marsh Harrier. Hamlyn Ltd., Lon- managementand recovery.The PeregrineFund, Inc, don, UK. Boise, ID U.S.A. 1996. Montagu's Harrier. Arlequin Press, WOFFINDEN,N.D. ANDJ.R.MURPHY. 1977. A roadsiderap- Chelmsford, Essex, UK. tor census in the eastern Great Basin--1973-1974. CUPPER,J. ANDL. CUPPER.1981. Hawks in focus:a study RaptorRes. 11:62-66. of Australia'sbirds of prey.Jaclin Enterprises,Mildu- ra, Australia. Received10 April 1997;accepted 11 August1997