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za de los resultados.Pages 118-119 in A. Hoffmann diet of the Rufous Legged Owls (Strix rufipes)in tem- [ED.], La tragedia del bosque chileno. Ocho Libros perate forestsremnants of southern . Ecoscience Editores, Santiago,Chile. 3:259-263. MA•N, G. 1978. Los pequefiosmamiferos de Chile. Gaya- • AND--'. 1997. Selectivepredation on scanso- na Zool.40, 342 pp. rial and arboreal mammals by Rufous-LeggedOwl MARTINEZ,D. 1993a. Food-habits of the Rufous-legged (Strix rufipes)in southern Chilean rainforest.J. Raptor Owl (Strix rufipes)in temperate rainforest of Southern Res. 31:370-375. Chile.J. RaptorRes. 27:214-216. MOONF•Y,H.A., E.L. DUNN, F. SHROSPSHIREAND L. SONG, 1993b. DepredaciGn selectira de roedores por Jl•. 1972. Land use historyof Californiaand Chile as zorrosy bfihosen la pluviselvavaldiviana. Resfimenes related to the structure of the sclerophyllscrub veg- del III Congreso Internacional de GestiGnen Recur- etations. Madrolo 21:305-319. sos Naturales, Puc0n, Chile. VUILLEUMIER,F. 1985. Forest of Patagonia:ecologi- 1996. Ecologia trGfica del ConcGn (Strix rufipes, cal geography,speciation, endemism, and faunal his- King 1828) y su respuestaa manipulacionesde frac- tory. Pages255-304 in P.A. Buckley,M.S. Foster,E.S. ciGn de sus presasen el bosque de "San Martin," Morton, R.S. Ridgely and EG. Buckley [EDs.], Neo- Valdivia, Chile. Tesis de Magister, Facultad de Cien- tropical ornithology.Ornithol. Monogz 36. cias, Universidad Austral de Chile, Valdivia, Chile. --),NO F.M. JAKSIC.1996. Habitat, abundance and Received7 October 1998;accepted 10 April 1999

J. RaptorRes. 33 (3) :264-267 ¸ 1999 The Raptor ResearchFoundation, Inc.

FOOD HABITS OF THE CINEREOUSHARRIER (CIRCUSC1NEREUS) IN THE ARAUCANiA, SOUTHERN CHILE

RICARDO A. FIGUEROA R. AND EMA S. CORALES S. Laboratoriode Ecologla, Departamento de CienciasBdsicas, Universidad de losLagos, Casilla 933, Osorno,Chile

KEYWORDS: CinereousHarri• Circuscinereus; food; Chile. reanalyzedby Iriarte et al. (1990). Here, we report the first quantitative data on food habits of the Cinereous The Cinereous (Circuscinereus) is widespread Harrier in an agricultural landscapeof the Araucania re- •n South America, ranging from northern to gion (ca. 38øS)in southernChile. Tlerra del Fuego in open areas such as marshes,grass- STUDY AREA AND METHODS lands,shrublands, and steppes(Jim•nez andJaksic1988, and references therein). In Chile, it is a resident along We studied two pairs of Cinereous Harriers in a 200- its entire distributionalrange from Copiap6 (30øS)to Ti- ha area at Tricauco Farm, located approximately6 km erra del Fuego (57øS) (Hellmayr 1932, Johnson 1965). south of Traigubn city (38ø14'S,72ø38'W) in the Arau- Its status varies from "rare" in northern Chile, to "fre- cania Region of Chile. The landscapecomprised crop- lands of wheat and corn, grasslands,marshlands, exotic quent" in central and southern Chile, to "abundant" in tree plantationsof Pinus spp. and Eucalyptusspp. and southernmostChile (JaksicandJim•nez 1986). Although remnants of the original deciduousNothofagus forest. The historical forest cutting and establishmentof croplands climate is moist-temperatewith a Mediterranean influ- has favorablyaffected the CinereousHarrier in southern ence (di Castri and Hajek 1976) and mean annual rain- Chile, current increasesof exotic pine and eucalyptus fall and temperatureare 1400 mm and 12øC,respectively. plantations and marsh draining for urban and agricul- Although originallythe Araucanfaregion extendedfrom tural developmentappear to negativelyimpact harriers Maule Province to Seno Reloncavl, the current Admin- by decreasingtheir hunting habitat, prey availabilityand istrativeAraucanfa Region extends from the RenaicoRiv- nest sites (Jaksicand Jim•nez 1986). er (37ø30'S)to Calafqu•nLake (38ø47'S). During August 1996 (austral winter), we collected68 Little is known about the biologyof this South Amer- pellets in abandonedpastures and marsheswhere harri- ican harrier, except for studiesconducted byJim•nez and ers hunted and perched. Pelletswere collectedboth from Jaksic (1988) in Chile and by Saggeseand De Lucca open ground in pasture-marshesand under trees,fences (1995) in . Data on its diet in the Magellanic and stumpsused as perchesby harriers. Avian prey were steppewere reported by Jim•nez and Jaksic (1988) and identified mainly on the basisof feathers, using two corn- SEPTEMBER1999 SHORT COMMUNICATIONS 265

Table 1. Food habitsof CinereousHarriers ( Circusdnereus) in an agriculturallandscape of the Araucania,southern Chile.

M•ss FREQUENCY BIOMASS PREY (g) (%) (%) Mammals 21.4 26.3 Rodentia Abrothrix olivaceus 23 4.4 0.9 Oligoryzomyslongicaudatus 26 2.7 0.6 Mus musculus 21 0.9 0.2 Unidentified rodents 23 10.7 2.2

Lagomorpha Oryctolagmscuniculus a.b 800 0.9 6.4 Lepuseuropaeus a,b 1000 1.8 16.0 Birds 67.0 73.3

Tinamiformes Nothoproctaperdicaria 160 2.7 3.8 Ciconiiformes Nycticoraxnycticorax • 600 0.9 4.8 Anseriformes Anasfiavirostris 400 0.9 3.2 Anasgeorgica 700 1.8 11.2 Falconiformes Milvagochimango b 100 0,9 0.8 Galliformes Callipeplacalifornica b 64 2.7 1.5 Charadriiformes Vanellus chilensis 270 3.5 8.6

Columbiformes Columbaaraucana 300 2.7 7.2 Zenaida auriculata 137 9.8 12.1

Passeriformes Troglodytesaedon 10 0.9 0.1 Turdusfalchlandii 90 14.3 11.5 Sicalis luteola 16 15.2 2.2 Sturnellaloyca 96 3.5 3.0 Curaeus curaeus 95 0.9 0.8 Phrygiluspatagonicus 38 0.9 0.3 Carduelis barbata 15 0.9 O.1 Unident. passeriformes 51 4.5 2.0 Reptiles 4.5 0.3 Liolaemusspp. 8 4.5 0.3 Insects 7.1 0.03 Coleoptera 0.5 3.5 0.01 Orthoptera 0.5 1.8 0.01 Unident. insects 0.5 1.8 0.01 Total prey items (N) 112 Total biomass(g) 12 502 Total pellets (N) 68 Likely juveniles. Introduced. 266 SHORT COMMUNICATIONS VOL. 33, NO. 3 plementary methods: microscopic analysisof feather malian biomass(22.4%). The incidence of reptiles and structuressuch as nodes and barbules (Reyes1992) and insectswas negligible both by number and biomass. comparisonof feather colorationpatterns with voucher Spearman rank correlation coefficientswere rs = 0.72 specimensdeposited in the ZoologyDepartment, Univer- sidad Austral de Chile at Valdivia and in the National (P < 0.01) when all bird prey specieswere considered, and rs = 0.94 (P = 0.02) when passerinesalone were Museum of Natural History at Santiago.Because we ob- considered. These trends indicated that Cinereous Har- served harriers eating birds entirely, we used the pres- ence of feathers of a given speciesin a pellet as repre- riers hunted avian prey opportunisticallyrather than se- senting only one individual. Mammals were identified lectively (i.e., they took avian prey in proportion to their and quantified on the basisof skullsor dentary pairs, availability). whichevergave the highestcount following keysin Reise Overall, our resultsagree with those of Jim•nez and (1973). Reptiles were identified and quantified by the Jaksic (1988), who reported that birds were the main presenceof scalesand/or teeth, and insectsby head cap- prey of Cinereous Harriers during the breeding season sules,mandibles or elytra following keysin Donoso-Bar- in steppe marshesof Magallanes, southernmostChile. ros (1966) and Pefia (1986), respectively.We identified Also, the diet of theseharriers was similar to that of Long- prey items to the finest possibletaxonomic category. Biomass contribution was estimated following Marti winged Harriers (Circusbuffoni) in Argentina (B6 et al. (1987). Masses of birds and small mammals were ob- 1996), indicating that South American harriers are essen- tained for birds usingJaksic et al. (1983), Morgado et al. tially predators. (1987), Jim•nez and Jaksic (1989) and Egli (1996) and for mammalsusing Greer (1968), Pearson (1983) and RESUMEN.--Determinamos la dieta del vari (Circus ciner- Martinez (1993). Massesof lagomorphswere obtained eus) en agroecosistemasde la Regi6n de la Araucania, from juveniles found killed by raptorssuch as Cinereous sur de Chile, analizando68 egagr6pilascolectadas en aso- Harriers and Short-earedOwls (Asioflammeus).Masses of lizards and insectswere obtained from unpublisheddata ciaciones de pastizal-humedaldurante el invierno de of the authors. We assumed that masses of unidentified 1996. Los varis consumieronun ampliD espectrode pre- prey were similar to the mean massof the most closely sas que incluy6 aves,mamiferos, reptiles e insectos.Sin related identified taxon. embargo, las avesrueton la base de la dieta (16 especies Although it was not possibleto obtain simultaneous presa),alcanzando 67% en frecuenciay 73% en biomasa. data on relative abundance of bird species,during the Entre •stas, las m/rs frecuentes fueron Sicalis luteola winter of 1997 we estimatedbird abundanceusing eight (15%), Turdusfalcklandii (14%) y Zenaida auriculata parallel, fixed-band (100 m wide) line transects(Bibby et (10%). En t•rminos de biomasa, Z. auriculatay T. falck- al 1993) placed 400 m apart in the hunting areas of landii hicieron una mayor contribuci6n a la dieta (ca. harriers. To testwhether harriers took birds selectivelyor 12% cada uno). Los mamiferos alcanzaron el 21% de la opportunistically,we compared prey frequency distribu- tion in pellets with bird abundance using Spearman's frecuenciay contribuyeroncon el 26% de la biomasa.La rank correlationsas recommendedby Jaksic(1979) for contribuci6n de reptiles e insectosfue poco relevante. coarsecomparisons between prey consumptionand avail- En general, nuestros resultados son coincidentes con ability. otros autores, quienes mencionan alas aves como las principalespresas de los varis en la Regi6n de Magalla- RESULTS AND DISCUSSION nes. Pelletsaveraged 28.2 + 1.9 (+SE) mm in length and [Traducci6n de Autores] 14 9 + 0.9 mm in width (N = 50) and had a mean dry weight of 1.0 + 0.6 g (N = 68). We identified 112 prey ACKNOWLEDGMENTS items in these pellets including 16 speciesof birds, five We thank the Zenhder Stappung family for permission speciesof mammals, one speciesof reptile and two or- to work in their lands and we are especiallygrateful to ders of insects.Birds were the staple prey comprising Olga Stappung for partially funding this study, and to 67% by frequencyand 73% by biomassof the diet. Most Lilian Stappung for logisticalsupport. In addition, we birds eaten were Passeriformes (41.1%) with Grassland wish to thank Roberto Schlatter and Juan c. Torres-Mura who kindly permitted accessto the collectionsin the Zo- Yellow-Finches (Sicalis luteola) and Austral Thrushes ( Tur- ologyDepartment of UniversidadAustral and Chile's Na- dusfalcklandii) being the most frequently eaten (Table tional Museum of Natural History, respectively.We also 1) Eared Doves (Zenaida auriculata)ranked third by fi'e- are grateful to David R. Martinez who allowed us to use quencybut, by biomass,Eared Dovesand AustralThrush- his facilities and to Jaime R. Rau for accessto his espe- es were the most important prey. This agreed with an- cialized literature. D.R. Martinez and J.R. Rau made use- ecdotal reports by Housse (1945), who indicated that ful suggestionsand criticismson earlier drafts and two Eared Doveswere the preferred prey of Cinereous Har- anonymous referees made valuable comments on the riers in southcentral Chile. Mammals were the second manuscript.

most common prey with olivaceousfield mice (Abrothrix LITERATURE CITED ohvaceus)and long-tailed rice rats (Olig0ryz0myslongicau- datus)the most frequent. However,because of their larg- BIBBY,C., N. BURGESAND D. HILL. 1993. Bird census tech- er size, lagomorphsaccounted for almost all of the mam- niques. Academic Press,London, U.K. SEPTEMBER1999 SHORT COMMUNICATIONS 267

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