Ecología y conservación del Aguilucho Langostero (Buteo swainsoni) en Argentina

José Hernán Sarasola; Maximiliano Adrián  Galmes; Miguel Ángel Santillán

doi:10.56178/eh.v22i2.765

Articles Published 01 December 2007 https://doi.org/10.56178/eh.v22i2.765

Ecology and conservation of Swainson’s Hawk (Buteo swainsoni) in Argentina

agroecosystems Buteo swainsoni conservation massive mortalities migration Swainson’s Hawk wintering grounds

José Hernán Sarasola Centro para el Estudio y Conservación de las Aves Rapaces en Argentina (CECARA), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de La Pampa. Avda. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina.

Maximiliano Adrián Galmes Centro para el Estudio y Conservación de las Aves Rapaces en Argentina (CECARA), Facultad de Ciencias Exactasy Naturales, Universidad Nacional de La Pampa. Avda. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina

Miguel Ángel Santillán Centro para el Estudio y Conservación de las Aves Rapaces en Argentina (CECARA), Facultad de Ciencias Exactasy Naturales, Universidad Nacional de La Pampa. Avda. Uruguay 151, 6300 Santa Rosa, La Pampa, Argentina

Abstract

Inthe mid-1990’s, the Swainson’s Hawk (Buteo swainsoni) turned into one of the most paradigmatic cases in relation to the potential effects of agricultural practices on wildlife in the Argentine pampas. Its habits of spatial segregation, prey and habitat selection, added to environmental conditions that determined demographic outbreaks of insect populations, most of them very prejudicial for crops and pastures implanted in this region, were factors that combined to resultin a series of poisoning incidents that affected approximately to 20 000 hawks, a 5% of the world population estimated in that moment. Despite the fact that the pesticide that caused thesemortality incidents has been banned from Argentina and new mortality incidents have not been reported in the area, several important aspects of the wintering ecology of the Swainson’s Hawk related with conservation planning are still unknown. In this paper we review the information available on the austral ecology of the Swainson’s Hawk, analyzing those conservation measures taken to avoid the occurrence of new mortality incidents and the achievement of extension,educational and research goals. The Swainson’s Hawk has become a “umbrella species” for the conservation of biodiversity in the agroecosystems of Argentina and all the efforts made topreserve wintering populations of this raptor surely have resulted in the conservation of otherbirds inhabiting these habitats.

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References

BEAUCHAMP G (1999) The evolution of communalroosting in birds: origin and secondary losses.Behavioral Ecology 10:675–687
BECHARD MJ, SARASOLA JH Y WOODBRIDGE B (2006) Are-evaluation of evidence raises questions about thefasting migration hypothesis for Swainson’s Hawk(Buteo swainsoni). Hornero 21:65–72
BLOOM PH (1980) The status of the Swainson’s hawk inCalifornia, 1979. Bureau of Land Management andFederal Aid in Wildlife Restoration, California De-partment of Fish and Game, Sacramento
BOLLMER J, KIMBALL RT, WHITEMAN NK, SARASOLA JHY PARKER PG (2006) Phylogeography of the Galápa-gos hawk: a recent arrival to the Galápagos Islands.Molecular Phylogenetics and Evolution 39:237–247
CANAVELLI SB (2000) Abundance, movement and habitatuse of Swainson’s hawks in their wintering grounds,Argentina. Tesis de Maestría, University of Florida,Gainsville
CANAVELLI SB, BECHARD MJ, WOODBRIDGE B, KOCHERTMN, MACEDA JJ Y ZACCAGNINI ME (2003) Habitat useby Swainson’s hawks on their austral winteringgrounds in Argentina. Journal of Raptor Research37:125–134
CANAVELLI SB, MACEDA JJ Y BOSISIO AC (2001) Dietadel Aguilucho Langostero (Buteo swainsoni) en suárea de invernada (La Pampa, Argentina). Hornero16:89–92
ENGLAND AS, BECHARD MJ Y HOUSTON CS (1997)Swainson’s Hawk (Buteo swainsoni). Pp. 1–28 en:POOLE A Y GILL F (eds) The birds of North America.Academy of Natural Sciences y American Orni-thologists’ Union, Filadelfia y Washington DC
FULLER MR, SEEGAR WS Y SCHUECK LS (1998) Routesand travel rates of migrating Peregrine Falcons Falcoperegrinus and Swainson’s Hawks Buteo swainsoniin the western hemisphere. Journal of Avian Biology29:433–440
GALMES MA (2006) Relaciones tróficas en un ensamblede rapaces con diferentes estatus de residencia enagroecosistemas de la Región Pampeana. Tesis deGrado, Universidad Nacional de La Pampa, SantaRosa
GOLDSTEIN MI (1997) Toxicological assessment of aNeotropical migrant on its non-breeding grounds: casestudy of the Swainson’s hawk in Argentina. Tesis deMaestría, Clemson University, Clemson
GOLDSTEIN MI, BECHARD MJ, PARKER ML, KOCHERT MNY LANUSSE AE (2000) Abundance, behavior, andmortality of Buteo swainsoni near San Francisco,Córdoba, Argentina in 1997. Hornero 15:117–121
GOLDSTEIN MI, BLOOM PH, SARASOLA JH Y LACHER TE(1999a) Post-migration weight gain of Swainson’sHawks in Argentina. Wilson Bulletin 111:428–432
GOLDSTEIN MI, LACHER TE JR, WOODBRIDGE B, BECHARDMJ, CANAVELLI SB, ZACCAGNINI ME, COBB GP,SCOLLON EJ, TRIBOLET R Y HOOPER MJ (1999b)Monocrotophos-induced mass mortality of Swain-son’s hawks in Argentina, 1995-96. Ecotoxicology8:201–214
GOLDSTEIN MI, LACHER TE JR, ZACCAGNINI ME, PARKERML Y HOOPER MJ (1999c) Monitoring and assess-ment of Swainson’s Hawks in Argentina followingrestrictions on monocrotophos use, 1996-97.Ecotoxicology 8:215–224
GOLDSTEIN MI, WOODBRIDGE B, ZACCAGNINI ME,CANAVELLI SG Y LANUSSE A (1996) An assessment ofmortality of Swainson’s hawks in winteringgrounds in Argentina. Journal of Raptor Research30:106–107
HERRON GB, MORTIMER CA Y RAWLINGS MS (1985)Nevada raptors: their biology and management. NevadaDepartment of Wildlife, Reno
HOOPER MJ, MINEAU P, ZACCAGNINI ME, WINEGRAD GWY WOODBRIDGE B (1999) Monocrotophos and theSwainson’s hawk. Pesticide Outlook 10:97–102
HOOPER MJ, MINEAU P, ZACCAGNINI ME Y WOODBRIDGEB (2002) Pesticides and international migratory birdconservation. Pp. 737–753 en: HOFFMAN DJ, RATTNERBA, BURTON GA JRY CAIRNS J JR (eds) Handbook ofecotoxicology. Segunda edición. Lewis Publishers,Boca Raton
HOUSTON CS Y SCHMUTZ JK (1995) Declining repro-duction among Swainson’s hawks in prairieCanada. Journal of Raptor Research 29:198–201
DEL HOYO J, ELLIOTT A Y SARGATAL J (1994) Handbook ofthe birds of the world. Volume 2. New World vultures toguineafowls. Lynx Edicions, Barcelona
HULL JM, ANDERSON R, BRADBURY M, ESTEP JA Y ERNESTHB (2008) Population structure and genetic diver-sity in Swainson’s Hawks (Buteo swainsoni): impli-cations for conservation. Conservation Genetics9:305–316
INDEC (2008) INDEC web. Instituto Nacional de Es-tadísticas y Censos, Buenos Aires (URL: http://www.indec.gov.ar/)JARAMILLO AP (1993) Wintering Swainson’s hawks inArgentina: food and age segregation. Condor95:475–479
JOHNSON CG, NICKERSON LA Y BECHARD MJ (1987)Grasshopper consumption and summer flocks ofnonbreeding Swainson’s hawks. Condor 89:676–678
KETTERSON ED Y NOLAN V JR (1983) The evolution ofdifferential bird migration. Current Ornithology1:357–402KIRKLEY JS (1991) Do migrant Swainson’s Hawks fasten route to Argentina? Journal of Raptor Research25:82–86
LAT TA SC Y BALTZ ME (1997) Population limitation inNeotropical migratory birds: comments on Rappoleand McDonald (1994). Auk 114:754–762
LITTLEFIELD CD, THOMPSON SP Y BRADLEY DE (1984)History and present status of Swainson’s hawks insoutheast Oregon. Journal of Raptor Research 18:1–5
MORELLO J, MATEUCCI SD Y RODRÍGUEZ A (2003)Sustainable development and urban growth in theArgentine Pampas region. Annals of the AmericanAcademy of Political and Social Science 590:115–130
NEWTON I (2004) Population limitation in migrants.Ibis 146:197–226
RAPPOLE JH Y MCDONALD MV (1994) Cause and effectin population declines of migratory birds. Auk111:652–660
RAPPOLE JH Y MCDONALD MV (1998) Response toLatta and Baltz (1997). Auk 115:246–251
RIESING MJ, KRUCKENHAUSER L, GAMAUF A Y HARING E(2003) Molecular phylogeny of the genus Buteo(Aves: Accipitridae) based in mitochondrial markersequences. Molecular Phylogenetics and Evolution27:328–342
RISEBROUGH RW, SCHLORFF RW, BLOOM PH Y LITTRELLEE (1989) Investigations of the decline of Swainson’shawk populations in California. Journal of RaptorResearch 23:63–71
ROBBINS CS, SAUER JR, GREENBERG RS Y DROEGE S(1989) Population declines in North American birdsthat migrate to the Neotropics. Proceedings of theNational Academy of Sciences 86:7658–7662
RUDOLPH DC Y FISHER CD (1993) Swainson’s hawkpredation on dragonflies in Argentina. Wilson Bul-letin 105:365–366
SARASOLA JH, BUSTAMANTE J, NEGRO JJ Y TRAVAINI A(2008a) Where do Swainson’s Hawks winter?Satellite images used to identify potential habitat.Diversity and Distributions 14:742–753
SARASOLA JH Y NEGRO JJ (2004) Gender identifica-tion in the Swainson’s Hawk Buteo swainsoniusing molecular procedures and discriminantfunction analysis. Journal of Raptor Research38:357–361
SARASOLA JH Y NEGRO JJ (2005) Hunting success ofwintering Swainson’s hawks: environmental effectson timing and choice of foraging method. CanadianJournal of Zoology 83:1353–1359
SARASOLA JH Y NEGRO JJ (2006) Role of exotic treestands on the current distribution and socialbehaviour of Swainson’s hawk, Buteo swainsoni, inthe Argentine Pampas. Journal of Biogeography33:1096–1101
SARASOLA JH, NEGRO JJ, HOBSON K, BORTOLOTTI GR YBILDSTEIN KL (2008b) Can a “wintering area effect”explain the population status of Swainson’s hawks?A stable isotope approach. Diversity and Distribu-tions 14:686–691
SARASOLA JH, NEGRO JJ, SALVADOR V Y MACEDA JJ (2005)Hailstorms as a cause of mass mortality of Swain-son’s hawks in their wintering grounds. Journal ofWildlife Diseases 41:643-646
SARASOLA JH, NEGRO JJ Y TRAVAINI A (2004) Nutri-tional condition and serum biochemistry for free-living Swainson’s Hawks wintering in CentralArgentina. Comparative Biochemistry and PhysiologyB 137:697–701
SERRACÍN ARAUJO R Y TIRANTI SI (1996) Stomach con-tents of a Swainson’s hawk from Argentina. Journalof Raptor Research 30:105–106
SIMBERLOFF D (1998) Flagships, umbrellas, and key-stones: is single-species management passé in thelandscape era? Biological Conservation 83:247–257
SMITH NG (1980) Hawk and vulture migration on theNeotropics. Pp. 51–65 en: KEAST A Y MORTON ES(eds) Migrant birds on the Neotropics: ecology, behav-ior, distribution and conservation. Smithsonian Insti-tution Press, Washington DC
SMITH NG, GOLDSTEIN DL Y BARTHOLOMEW GA (1986)Is long-distance migration possible using onlystored fat? Auk 103:607–611
SORIANO A (1992) Río de la Plata grasslands. Pp.367–407 en: COUPLAND RT (ed) Ecosystems of theworld. 8A. Natural grasslands: introduction and West-ern Hemisphere. Elsevier, Amsterdam
TORRUSIO S, CIGLIANO MM YDE WYSIECKI ML (2002)Grasshopper (Orthoptera: Acridoidea) and plantcommunity relationships in the Argentine pampas.Journal of Biogeography 29:221–229
UHART M Y ZACCAGNINI ME (1999) Manual de procedi-mientos operativos estandarizados de campo para docu-mentar incidentes de mortandad de fauna silvestre enagroecosistemas. INTA, Buenos Aires
VIGLIZZO EF (1994) The response of low-imput agri-cultural systems to environmental variability: atheoretical approach. Agriculture Systems 44:1–17
VIGLIZZO EF, ROBERTO ZE, LÉRTORA F, LÓPEZ-GAY E YBERNARDOS J (1997) Climate and land-use change infield-crop ecosystems of Argentina. Agriculture Eco-systems and Environment 66:61–70
WHEELER BK Y CLARK WS (1995) A photographic guideto North American raptors. Academic Press, San Diego
WHITE CM, BOYCE DA Y STRANECK R (1989) Observa-tions on Buteo swainsoni in Argentina, 1984, withcomments on food, habitat alteration, and agricul-tural chemicals. Pp. 79–87 en: MEYBURG B-U Y CHAN-CELLOR RD (eds) Raptors in the modern world. Pro-ceedings of the III World Conference on Birds of Preyand Owls. Eilat, Israel, 22–27 March 1987. World Work-ing Group on Birds of Prey, Berlín, Londres y París
WOODBRIDGE B, FINLEY KK Y SEAGER ST (1995) An in-vestigation of the Swainson’s Hawk in Argentina.Journal of Raptor Research 29:202–204
ZACCAGNINI ME (2001) Agricultura y conservación: elAguilucho Langostero de Argentina. Pp. 212–213 en:PRIMACK R, ROZZI R, FEINSINGER P, DIRZO R YMASSARDO F (eds) Fundamentos de conservación bioló-gica. Perspectivas latinoamericanas. Fondo de CulturaEconómica, México DF
ZACCAGNINI ME (2004) ¿Porqué monitoreo ecotoxico-lógico de diversidad de aves en sistemas producti-vos?Pp. 69–89 en: LARREA E (ed) INTA expone 2004.Volumen III. INTA, Buenos Aires

How to cite

José Hernán Sarasola, Maximiliano Adrián Galmes, Miguel Ángel Santillán (2007). Ecology and conservation of Swainson’s Hawk (Buteo swainsoni) in Argentina. El Hornero, Vol. 22 No. 2 (2007), 173-184. https://doi.org/10.56178/eh.v22i2.765

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[1] BEAUCHAMP G (1999) The evolution of communalroosting in birds: origin and secondary losses.Behavioral Ecology 10:675–687

[2] BECHARD MJ, SARASOLA JH Y WOODBRIDGE B (2006) Are-evaluation of evidence raises questions about thefasting migration hypothesis for Swainson’s Hawk(Buteo swainsoni). Hornero 21:65–72

[3] BLOOM PH (1980) The status of the Swainson’s hawk inCalifornia, 1979. Bureau of Land Management andFederal Aid in Wildlife Restoration, California De-partment of Fish and Game, Sacramento

[4] BOLLMER J, KIMBALL RT, WHITEMAN NK, SARASOLA JHY PARKER PG (2006) Phylogeography of the Galápa-gos hawk: a recent arrival to the Galápagos Islands.Molecular Phylogenetics and Evolution 39:237–247

[5] CANAVELLI SB (2000) Abundance, movement and habitatuse of Swainson’s hawks in their wintering grounds,Argentina. Tesis de Maestría, University of Florida,Gainsville

[6] CANAVELLI SB, BECHARD MJ, WOODBRIDGE B, KOCHERTMN, MACEDA JJ Y ZACCAGNINI ME (2003) Habitat useby Swainson’s hawks on their austral winteringgrounds in Argentina. Journal of Raptor Research37:125–134

[7] CANAVELLI SB, MACEDA JJ Y BOSISIO AC (2001) Dietadel Aguilucho Langostero (Buteo swainsoni) en suárea de invernada (La Pampa, Argentina). Hornero16:89–92

[8] ENGLAND AS, BECHARD MJ Y HOUSTON CS (1997)Swainson’s Hawk (Buteo swainsoni). Pp. 1–28 en:POOLE A Y GILL F (eds) The birds of North America.Academy of Natural Sciences y American Orni-thologists’ Union, Filadelfia y Washington DC

[9] FULLER MR, SEEGAR WS Y SCHUECK LS (1998) Routesand travel rates of migrating Peregrine Falcons Falcoperegrinus and Swainson’s Hawks Buteo swainsoniin the western hemisphere. Journal of Avian Biology29:433–440

[10] GALMES MA (2006) Relaciones tróficas en un ensamblede rapaces con diferentes estatus de residencia enagroecosistemas de la Región Pampeana. Tesis deGrado, Universidad Nacional de La Pampa, SantaRosa

[11] GOLDSTEIN MI (1997) Toxicological assessment of aNeotropical migrant on its non-breeding grounds: casestudy of the Swainson’s hawk in Argentina. Tesis deMaestría, Clemson University, Clemson

[12] GOLDSTEIN MI, BECHARD MJ, PARKER ML, KOCHERT MNY LANUSSE AE (2000) Abundance, behavior, andmortality of Buteo swainsoni near San Francisco,Córdoba, Argentina in 1997. Hornero 15:117–121

[13] GOLDSTEIN MI, BLOOM PH, SARASOLA JH Y LACHER TE(1999a) Post-migration weight gain of Swainson’sHawks in Argentina. Wilson Bulletin 111:428–432

[14] GOLDSTEIN MI, LACHER TE JR, WOODBRIDGE B, BECHARDMJ, CANAVELLI SB, ZACCAGNINI ME, COBB GP,SCOLLON EJ, TRIBOLET R Y HOOPER MJ (1999b)Monocrotophos-induced mass mortality of Swain-son’s hawks in Argentina, 1995-96. Ecotoxicology8:201–214

[15] GOLDSTEIN MI, LACHER TE JR, ZACCAGNINI ME, PARKERML Y HOOPER MJ (1999c) Monitoring and assess-ment of Swainson’s Hawks in Argentina followingrestrictions on monocrotophos use, 1996-97.Ecotoxicology 8:215–224

[16] GOLDSTEIN MI, WOODBRIDGE B, ZACCAGNINI ME,CANAVELLI SG Y LANUSSE A (1996) An assessment ofmortality of Swainson’s hawks in winteringgrounds in Argentina. Journal of Raptor Research30:106–107

[17] HERRON GB, MORTIMER CA Y RAWLINGS MS (1985)Nevada raptors: their biology and management. NevadaDepartment of Wildlife, Reno

[18] HOOPER MJ, MINEAU P, ZACCAGNINI ME, WINEGRAD GWY WOODBRIDGE B (1999) Monocrotophos and theSwainson’s hawk. Pesticide Outlook 10:97–102

[19] HOOPER MJ, MINEAU P, ZACCAGNINI ME Y WOODBRIDGEB (2002) Pesticides and international migratory birdconservation. Pp. 737–753 en: HOFFMAN DJ, RATTNERBA, BURTON GA JRY CAIRNS J JR (eds) Handbook ofecotoxicology. Segunda edición. Lewis Publishers,Boca Raton

[20] HOUSTON CS Y SCHMUTZ JK (1995) Declining repro-duction among Swainson’s hawks in prairieCanada. Journal of Raptor Research 29:198–201

[21] DEL HOYO J, ELLIOTT A Y SARGATAL J (1994) Handbook ofthe birds of the world. Volume 2. New World vultures toguineafowls. Lynx Edicions, Barcelona

[22] HULL JM, ANDERSON R, BRADBURY M, ESTEP JA Y ERNESTHB (2008) Population structure and genetic diver-sity in Swainson’s Hawks (Buteo swainsoni): impli-cations for conservation. Conservation Genetics9:305–316

[23] INDEC (2008) INDEC web. Instituto Nacional de Es-tadísticas y Censos, Buenos Aires (URL: http://www.indec.gov.ar/)JARAMILLO AP (1993) Wintering Swainson’s hawks inArgentina: food and age segregation. Condor95:475–479

[24] JOHNSON CG, NICKERSON LA Y BECHARD MJ (1987)Grasshopper consumption and summer flocks ofnonbreeding Swainson’s hawks. Condor 89:676–678

[25] KETTERSON ED Y NOLAN V JR (1983) The evolution ofdifferential bird migration. Current Ornithology1:357–402KIRKLEY JS (1991) Do migrant Swainson’s Hawks fasten route to Argentina? Journal of Raptor Research25:82–86

[26] LAT TA SC Y BALTZ ME (1997) Population limitation inNeotropical migratory birds: comments on Rappoleand McDonald (1994). Auk 114:754–762

[27] LITTLEFIELD CD, THOMPSON SP Y BRADLEY DE (1984)History and present status of Swainson’s hawks insoutheast Oregon. Journal of Raptor Research 18:1–5

[28] MORELLO J, MATEUCCI SD Y RODRÍGUEZ A (2003)Sustainable development and urban growth in theArgentine Pampas region. Annals of the AmericanAcademy of Political and Social Science 590:115–130

[29] NEWTON I (2004) Population limitation in migrants.Ibis 146:197–226

[30] RAPPOLE JH Y MCDONALD MV (1994) Cause and effectin population declines of migratory birds. Auk111:652–660

[31] RAPPOLE JH Y MCDONALD MV (1998) Response toLatta and Baltz (1997). Auk 115:246–251

[32] RIESING MJ, KRUCKENHAUSER L, GAMAUF A Y HARING E(2003) Molecular phylogeny of the genus Buteo(Aves: Accipitridae) based in mitochondrial markersequences. Molecular Phylogenetics and Evolution27:328–342

[33] RISEBROUGH RW, SCHLORFF RW, BLOOM PH Y LITTRELLEE (1989) Investigations of the decline of Swainson’shawk populations in California. Journal of RaptorResearch 23:63–71

[34] ROBBINS CS, SAUER JR, GREENBERG RS Y DROEGE S(1989) Population declines in North American birdsthat migrate to the Neotropics. Proceedings of theNational Academy of Sciences 86:7658–7662

[35] RUDOLPH DC Y FISHER CD (1993) Swainson’s hawkpredation on dragonflies in Argentina. Wilson Bul-letin 105:365–366

[36] SARASOLA JH, BUSTAMANTE J, NEGRO JJ Y TRAVAINI A(2008a) Where do Swainson’s Hawks winter?Satellite images used to identify potential habitat.Diversity and Distributions 14:742–753

[37] SARASOLA JH Y NEGRO JJ (2004) Gender identifica-tion in the Swainson’s Hawk Buteo swainsoniusing molecular procedures and discriminantfunction analysis. Journal of Raptor Research38:357–361

[38] SARASOLA JH Y NEGRO JJ (2005) Hunting success ofwintering Swainson’s hawks: environmental effectson timing and choice of foraging method. CanadianJournal of Zoology 83:1353–1359

[39] SARASOLA JH Y NEGRO JJ (2006) Role of exotic treestands on the current distribution and socialbehaviour of Swainson’s hawk, Buteo swainsoni, inthe Argentine Pampas. Journal of Biogeography33:1096–1101

[40] SARASOLA JH, NEGRO JJ, HOBSON K, BORTOLOTTI GR YBILDSTEIN KL (2008b) Can a “wintering area effect”explain the population status of Swainson’s hawks?A stable isotope approach. Diversity and Distribu-tions 14:686–691

[41] SARASOLA JH, NEGRO JJ, SALVADOR V Y MACEDA JJ (2005)Hailstorms as a cause of mass mortality of Swain-son’s hawks in their wintering grounds. Journal ofWildlife Diseases 41:643-646

[42] SARASOLA JH, NEGRO JJ Y TRAVAINI A (2004) Nutri-tional condition and serum biochemistry for free-living Swainson’s Hawks wintering in CentralArgentina. Comparative Biochemistry and PhysiologyB 137:697–701

[43] SERRACÍN ARAUJO R Y TIRANTI SI (1996) Stomach con-tents of a Swainson’s hawk from Argentina. Journalof Raptor Research 30:105–106

[44] SIMBERLOFF D (1998) Flagships, umbrellas, and key-stones: is single-species management passé in thelandscape era? Biological Conservation 83:247–257

[45] SMITH NG (1980) Hawk and vulture migration on theNeotropics. Pp. 51–65 en: KEAST A Y MORTON ES(eds) Migrant birds on the Neotropics: ecology, behav-ior, distribution and conservation. Smithsonian Insti-tution Press, Washington DC

[46] SMITH NG, GOLDSTEIN DL Y BARTHOLOMEW GA (1986)Is long-distance migration possible using onlystored fat? Auk 103:607–611

[47] SORIANO A (1992) Río de la Plata grasslands. Pp.367–407 en: COUPLAND RT (ed) Ecosystems of theworld. 8A. Natural grasslands: introduction and West-ern Hemisphere. Elsevier, Amsterdam

[48] TORRUSIO S, CIGLIANO MM YDE WYSIECKI ML (2002)Grasshopper (Orthoptera: Acridoidea) and plantcommunity relationships in the Argentine pampas.Journal of Biogeography 29:221–229

[49] UHART M Y ZACCAGNINI ME (1999) Manual de procedi-mientos operativos estandarizados de campo para docu-mentar incidentes de mortandad de fauna silvestre enagroecosistemas. INTA, Buenos Aires

[50] VIGLIZZO EF (1994) The response of low-imput agri-cultural systems to environmental variability: atheoretical approach. Agriculture Systems 44:1–17

[51] VIGLIZZO EF, ROBERTO ZE, LÉRTORA F, LÓPEZ-GAY E YBERNARDOS J (1997) Climate and land-use change infield-crop ecosystems of Argentina. Agriculture Eco-systems and Environment 66:61–70

[52] WHEELER BK Y CLARK WS (1995) A photographic guideto North American raptors. Academic Press, San Diego

[53] WHITE CM, BOYCE DA Y STRANECK R (1989) Observa-tions on Buteo swainsoni in Argentina, 1984, withcomments on food, habitat alteration, and agricul-tural chemicals. Pp. 79–87 en: MEYBURG B-U Y CHAN-CELLOR RD (eds) Raptors in the modern world. Pro-ceedings of the III World Conference on Birds of Preyand Owls. Eilat, Israel, 22–27 March 1987. World Work-ing Group on Birds of Prey, Berlín, Londres y París

[54] WOODBRIDGE B, FINLEY KK Y SEAGER ST (1995) An in-vestigation of the Swainson’s Hawk in Argentina.Journal of Raptor Research 29:202–204

[55] ZACCAGNINI ME (2001) Agricultura y conservación: elAguilucho Langostero de Argentina. Pp. 212–213 en:PRIMACK R, ROZZI R, FEINSINGER P, DIRZO R YMASSARDO F (eds) Fundamentos de conservación bioló-gica. Perspectivas latinoamericanas. Fondo de CulturaEconómica, México DF

[56] ZACCAGNINI ME (2004) ¿Porqué monitoreo ecotoxico-lógico de diversidad de aves en sistemas producti-vos?Pp. 69–89 en: LARREA E (ed) INTA expone 2004.Volumen III. INTA, Buenos Aires