Depredadores de nidos en pastizales del Parque Provincial Ernesto Tornquist (provincia de Buenos Aires, Argentina): importancia relativa bajo distintas intensidades de pastoreo

Natalia Cozzani; Sergio M. Zalba

doi:10.56178/eh.v27i2.652

Articles Published 01 December 2012 https://doi.org/10.56178/eh.v27i2.652

Nest predators in grasslands at Ernesto Tornquist Provincial Park (Buenos Aires province, Argentina): their relative importance under different grazing intensities

artificial nests conservation grassland birds predation

Natalia Cozzani GEKKO, Grupo de Estudios en Conservación y Manejo, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur. San Juan 670, 8000 Bahía Blanca, Buenos Aires, Argentina

Sergio M. Zalba GEKKO, Grupo de Estudios en Conservación y Manejo, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur. San Juan 670, 8000 Bahía Blanca, Buenos Aires, Argentina

Abstract

Natural grasslands are facing a rapid reduction, mainly due to the advance of agriculture, cattle ranching and urbanization, and this has lead to the decline of many bird species. Ernesto Tornquist Provincial Park (Buenos Aires Province, Argentina) holds a population of feral horses responsible of an intense grazing pressure resulting in changes in the structure and composition of plant communities. During three breeding seasons we identified groups of nest predators associated to different grazing situations. We carried out artificial nest experiments using both Quail and plasticine eggs simulating clutches of grassland birds. Egg remains were compared with a reference collection in order to determine the group of predators that consumed them. From a total of 612 eggs used during the three years, 27.5% failed. In order of importance, nest failures were due to missing eggs, predation by large mammals, predation by small mammals, predation by birds, cattle trampling, consumption by unidentified predators, and predation by snakes. Predator assemblages would be different under different grazing pressure conditions, resulting in a differential effect on bird breeding success.

PDF (Spanish)

References

ANDRÉN H (1992) Corvid density and nest predationin relation to forest fragmentation: a landscapeperspective. Ecology 73:794–804
ASKINS RA, CHÁVEZ-RAMÍREZ F, DALE BC, HAAS CA,HERKERT JR, KNOPF FL Y VICKERY PD (2007) Conser-vation of grassland birds in North America: under-standing ecological processes in different regions.Ornithological Monographs 64:1–46
BAKER BW, STANLEY TR Y SEDGWICK JA (1999) Preda-tion of artificial ground nests on White-Tailed PrairieDog colonies. Journal of Wildlife Management63:270–277
BATÁRY P, BÁLDI A Y ERDÓS S (2007) The effects of usingdifferent species conservation priority lists on theevaluation of habitat importance within Hungar-ian grasslands. Bird Conservation International17:35–43
BERGIN TM, BEST LB Y FREEMARK KE (1997) An experi-mental study of predation on artificial nests inroadsides adjacent to agricultural habitats in Iowa.Wilson Bulletin 109:437–448
BERRY L Y LILL A (2003) Do predation rates on artifi-cial nests accurately predict predation rates onnatural nests? The effects of nest type, egg type andnest-site characteristics. Emu 103:207–214
BEST LB (1978) Field sparrow reproductive successand nesting ecology. Auk 95:9–22
BOLTON M, BUTCHER N, SHARPE F, STEVENS D Y FISHERG (2007) Remote monitoring of nests using digitalcamera technology. Journal of Field Ornithology78:213–220
BORGES FJA Y MARINI MÂ (2010) Birds nesting survivalin disturbed and protected Neotropical savannas.Biodiversity and Conservation 19:223–236
BOWLES M (1993) Long-term grazing effects on sandprairie and grassland bird habitat at the Savanna ArmyDepot: with recommendations for management andrecovery. Morton Arboretum, Lisle
BURGOS J (1968) El clima de la provincia de BuenosAires en relación con la vegetación natural y el suelo.Pp. 33–100 en: CABRERA AL (ed) Flora de la provinciade Buenos Aires. INTA, Buenos Aires
CABRERA AL (1976) Regiones fitogeográficas argenti-nas. Pp. 1–85 en: Enciclopedia argentina de agriculturay ganadería. Tomo II, Fascículo 1. ACME, Buenos Aires
CARTER GM, LEGARE ML, BREININGER DR Y ODDY DM(2007) Nocturnal nest predation: a potential obsta-cle to recovery of a Florida Scrub-Jay population.Journal of Field Ornithology 78:390–394
CASANAVE EB, MANFREDI MC Y LUENGOS VIDAL EM(2003) Ecología comportamental de los armadillosen un pastizal serrano. Pp. 115–125 en: Anales de lasSegundas Jornadas Interdisciplinarias del SudoesteBonaerense. Tomo 3. Editorial de la UniversidadNacional del Sur, Bahía Blanca
CHALFOUN AD, RATNASWAMY MJ Y THOMPSON FR(2002) Songbird nest predators in forest-pastureedge and forest interior in a fragmented landscape.Ecological Applications 12:858–867
COMPARATORE VM, MARTÍNEZ MM, VASSALLO AI, BARGM Y ISACCH JP (1996) Abundancia y relaciones conel hábitat de aves y mamíferos en pastizales dePaspalum quadrifarium (paja colorada) manejadoscon fuego (Provincia de Buenos Aires, Argentina).Interciencia 21:228–237
COZZANI N (2010) Efectos del pastoreo sobre el éxito decría de aves de pastizal pampeano. Tesis de doctorado,Universidad Nacional del Sur, Bahía Blanca
COZZANI N, ZALBA SM Y MATTOS E (2009) Nidificaciónde aves de pastizal en el Parque Provincial E.Tornquist. Pp. 457–472 en:
CAZZANIGA NJ Y ARELO-VICH HM (eds) Ambientes y recursos naturales del sud-oeste bonaerense: producción, contaminación y conser-vación. Editorial de la Universidad Nacional del Sur,Bahía Blanca
DAVISON WB Y BOLLINGER E (2000) Predation rates onreal and artificial nests of grassland birds. Auk117:147–153
DI GIACOMO AS (2005) Áreas importantes para la conser-vación de las aves en Argentina. Sitios prioritarios parala conservación de la biodiversidad. Aves Argentinas/Asociación Ornitológica del Plata, Buenos Aires
DION N, HOBSON KA Y LARIVIÈRE S (2000) Interactiveeffects of vegetation and predators on the successof natural and simulated nests of grassland song-birds. Condor 102:629–634
DONOVAN TM, JONES PW, ANNAND EM Y THOMPSONFR III (1997) Variation in local scale edge effects:mechanisms and landscape context. Ecology78:2064–2075
ERIKSSON LM, EDENIUS L, ARESKOUG V Y MERITT DA JR(2001) Nest-predation at the edge: an experimentalstudy contrasting two types of edges in the dryChaco, Paraguay. Ecography 24:742–750
FRANÇA LF Y MARINI MÂ (2009) Teste do efeito deborda na predação de ninhos naturais e artificiaisno cerrado do Planalto Central, Brasil. RevistaBrasileira de Zoologia 26:241–250
FRANÇA LF, SOUSA NOM, DOS SANTOS LR, DUCA C,GRESSLER DT, BORGES FJA, LOPES LE, MANICA LT,PAIVA LV, DE MEDEIROS RCS Y MARINI MÂ (2009)Passeriformes: nest predators and prey in a Neo-tropical savanna. Revista Brasileira de Zoologia26:799–802
GABELLI FM, FERNÁNDEZ GJ, FERRETTI V, POSSE G,COCONIER E, GAVIEIRO HJ, LLAMBÍAS PE, PELÁEZ PI,VALLÉS ML Y TUBARO PL (2004) Range contractionin the pampas meadowlark Sturnella defilippii in thesouthern pampas grasslands of Argentina. Oryx38:164–170
GATES JE Y GYSEL LW (1978) Avian nest dispersion andfledging success in field-forest ecotones. Ecology59:871–873
GITHIRU M, LENS L Y CRESSWELL W (2005) Nest preda-tion in a fragmented Afrotropical forest: evidencefrom natural and artificial nests. Biological Conser-vation 123:189–196
HASKELL DG (1995) Forest fragmentation and nestpredation: are experiments with Japanese Quaileggs misleading? Auk 112:767–770
HERNANDEZ F, ROLLINS D Y CANTU R (1997) Evaluat-ing evidence to identify ground-nesting preda-tors in west Texas. Wildlife Society Bulletin25:826–831
KOZMA JM Y MATHEWS NE (1997) Breeding birdcommunities and nest plant selection in Chihua-huan desert habitats in South-Central New Mexico.Wilson Bulletin 109:424–436
LARIVIÈRE S Y MESSIER F (1998) Effect of density andnearest neighbours on simulated waterfowl nests:can predators recognize high-density nestingpatches? Oikos 83:12–20
LEGENDRE P Y LEGENDRE L (1998) Numerical ecology.Segunda edición. Elsevier, Amsterdam
LOYDI A, DISTEL RA Y ZALBA SM (2010) Large herbivoregrazing and non-native plant invasions in montanegrasslands of central Argentina. Natural Areas Jour-nal 30:148–155
LOYDI A Y ZALBA SM (2009) Feral horses dung piles asinvasion windows in natural grasslands. PlantEcology 201:471–480
LUENGOS VIDAL EM (2003) Estudio comparado demetodologías de captura y de estimación de las poblacio-nes de zorro pampeano: Pseudalopex gymnocercus. Tesisde magister, Universidad Nacional del Sur, BahíaBlanca
MAHAN HD (1956) Nocturnal predation on SongSparrow eggs by Milk Snake. Wilson Bulletin 68:245
MAIER TJ Y DEGRAAF RM (2000) Predation on Japanesequail vs. House sparrow eggs in artificial nests: smalleggs reveal small predators. Condor 102:325–332
MAJOR RE Y KENDAL CE (1996) The contribution ofartificial nest experiments to understanding avianreproductive success: a review of methods andconclusions. Ibis 138:298–307
MARINI MÂ Y MELO C (1998) Predators of quail eggs,and the evidence of the remains: implications fornest predation studies. Condor 100:395–399
MARTIN TE (1987) Food as a limit on breeding birds: alife-history perspective. Annual Review of Ecology andSystematics 18:453–487
MARTIN TE (1993) Nest predation and nest sites. Newperspectives on old patterns. BioScience 43:523–532
MARTIN TE Y LI P (1992) Life history traits of open- vs.cavity-nesting birds. Ecology 73:579–592
MEZQUIDA ET Y MARONE L (2002) Microhabitat struc-ture and avian nest predation risk in an openArgentinean woodland: an experimental study. ActaOecologica 23:313–320
MEZQUIDA ET Y MARONE L (2003) Are results of artifi-cial nest experiments a valid indicator of success ofnatural nests? Wilson Bulletin 115:270–276
MOORE RP Y ROBINSON WD (2004) Artificial bird nests,external validity, and bias in ecological field stud-ies. Ecology 85:1562–1567
MULLIN SJ Y COOPER RJ (1998) The foraging ecologyof the Gray Rat Snake (Elaphe obsoleta spiloides) —visual stimuli facilitate location of arboreal prey.American Midland Naturalist 140:397–401
MURPHY MT (2003) Avian population trends withinthe evolving agricultural landscape of eastern andcentral United States. Auk 120:20–34
NACK JL (2002) Effects of predators and cattle on ground-nesting grassland birds in southwestern Wisconsin pastures.Tesis de maestría, University of Wisconsin, Madison
NACK JL Y RIBIC CA (2005) Apparent predation bycattle at grassland bird nests. Wilson Bulletin117:56–62
ORTEGA CP, ORTEGA JC, RAPP CA Y BACKENSTO SA(1998) Validating the use of artificial nests in preda-tion experiments. Journal of Wildlife Management62:925–932
PÄRT T Y WRETENBERG J (2002) Do artificial nests revealrelative nest predation risk on real nests? Journal ofAvian Biology 33:39–46
PATON P (1994) The effect of edge on avian nestsuccess how strong is the evidence? ConservationBiology 8:17–26
DELA PEÑA MR (2005) Reproducción de las aves argenti-nas (con descripción de pichones). LOLA, Buenos Aires
RENFREW RB Y RIBIC CA (2003) Grassland passerinenest predators near pasture edges identified onvideotape. Auk 120:371–383
RENFREW RB, RIBIC CA Y NACK JL (2005) Edge avoid-ance by nesting grassland birds: a futile strategy ina fragmented landscape. Auk 122:618–636
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SCHMIDT KA, GOHEEN JR, NAUMANN R, OSTFELD RS,SCHAUBER EM Y BERKOWITZ A (2001) Experimentalremoval of strong and weak predators: mice andchipmunks preying on songbird nests. Ecology82:2927–2936
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SVAGELJ WS, MERMOZ ME Y FERNÁNDEZ GJ (2003) Effectof egg type on the estimation of nest predation inpasserines. Journal of Field Ornithology 74:243–249
THOMPSON FR III Y BURHANS DE (2004) Differences inpredators of artificial and real songbird nests:evidence of bias in artificial nest studies. Conserva-tion Biology 18:373–380
THOMPSON FR III, DIJAK W Y BURHANS DE (1999) Videoidentification of predators at songbird nests in oldfields. Auk 116:259–264VANDER HAEGEN WM, SCHROEDER MA Y DEGRAAF RM(2002) Predation on real and artificial nests inshrubsteppe landscapes fragmented by agriculture.Condor 104:496–506
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DE VILLALOBOS AE Y ZALBA SM (2010) Continuous feralhorses grazing and grazing exclusion in mountainpampean grasslands in Argentina. Acta Oecologica36:514–519
WEATHERHEAD PJ Y BLOUIN-DEMERS G (2004) Under-standing avian nest predation: why ornithologistsshould study snakes. Journal of Avian Biology35:185–190
WILLEBRAND T Y MARCSTRÖM V (1988) On the dangerof using dummy nests to study predation. Auk105:378–379
WILLSON M, MORRISON JL, SIEVING KE, DE SANTO TL,SANTISTEBAN L Y DÍAZ I (2001) Patterns of predationrisk and survival of birds nests in a Chilean agricul-tural landscape. Conservation Biology 15:447–456
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How to cite

Natalia Cozzani , Sergio M. Zalba (2012). Nest predators in grasslands at Ernesto Tornquist Provincial Park (Buenos Aires province, Argentina): their relative importance under different grazing intensities. El Hornero, Vol. 27 No. 2 (2012), 137-148. https://doi.org/10.56178/eh.v27i2.652

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[1] ANDRÉN H (1992) Corvid density and nest predationin relation to forest fragmentation: a landscapeperspective. Ecology 73:794–804

[2] ASKINS RA, CHÁVEZ-RAMÍREZ F, DALE BC, HAAS CA,HERKERT JR, KNOPF FL Y VICKERY PD (2007) Conser-vation of grassland birds in North America: under-standing ecological processes in different regions.Ornithological Monographs 64:1–46

[3] BAKER BW, STANLEY TR Y SEDGWICK JA (1999) Preda-tion of artificial ground nests on White-Tailed PrairieDog colonies. Journal of Wildlife Management63:270–277

[4] BATÁRY P, BÁLDI A Y ERDÓS S (2007) The effects of usingdifferent species conservation priority lists on theevaluation of habitat importance within Hungar-ian grasslands. Bird Conservation International17:35–43

[5] BERGIN TM, BEST LB Y FREEMARK KE (1997) An experi-mental study of predation on artificial nests inroadsides adjacent to agricultural habitats in Iowa.Wilson Bulletin 109:437–448

[6] BERRY L Y LILL A (2003) Do predation rates on artifi-cial nests accurately predict predation rates onnatural nests? The effects of nest type, egg type andnest-site characteristics. Emu 103:207–214

[7] BEST LB (1978) Field sparrow reproductive successand nesting ecology. Auk 95:9–22

[8] BOLTON M, BUTCHER N, SHARPE F, STEVENS D Y FISHERG (2007) Remote monitoring of nests using digitalcamera technology. Journal of Field Ornithology78:213–220

[9] BORGES FJA Y MARINI MÂ (2010) Birds nesting survivalin disturbed and protected Neotropical savannas.Biodiversity and Conservation 19:223–236

[10] BOWLES M (1993) Long-term grazing effects on sandprairie and grassland bird habitat at the Savanna ArmyDepot: with recommendations for management andrecovery. Morton Arboretum, Lisle

[11] BURGOS J (1968) El clima de la provincia de BuenosAires en relación con la vegetación natural y el suelo.Pp. 33–100 en: CABRERA AL (ed) Flora de la provinciade Buenos Aires. INTA, Buenos Aires

[12] CABRERA AL (1976) Regiones fitogeográficas argenti-nas. Pp. 1–85 en: Enciclopedia argentina de agriculturay ganadería. Tomo II, Fascículo 1. ACME, Buenos Aires

[13] CARTER GM, LEGARE ML, BREININGER DR Y ODDY DM(2007) Nocturnal nest predation: a potential obsta-cle to recovery of a Florida Scrub-Jay population.Journal of Field Ornithology 78:390–394

[14] CASANAVE EB, MANFREDI MC Y LUENGOS VIDAL EM(2003) Ecología comportamental de los armadillosen un pastizal serrano. Pp. 115–125 en: Anales de lasSegundas Jornadas Interdisciplinarias del SudoesteBonaerense. Tomo 3. Editorial de la UniversidadNacional del Sur, Bahía Blanca

[15] CHALFOUN AD, RATNASWAMY MJ Y THOMPSON FR(2002) Songbird nest predators in forest-pastureedge and forest interior in a fragmented landscape.Ecological Applications 12:858–867

[16] COMPARATORE VM, MARTÍNEZ MM, VASSALLO AI, BARGM Y ISACCH JP (1996) Abundancia y relaciones conel hábitat de aves y mamíferos en pastizales dePaspalum quadrifarium (paja colorada) manejadoscon fuego (Provincia de Buenos Aires, Argentina).Interciencia 21:228–237

[17] COZZANI N (2010) Efectos del pastoreo sobre el éxito decría de aves de pastizal pampeano. Tesis de doctorado,Universidad Nacional del Sur, Bahía Blanca

[18] COZZANI N, ZALBA SM Y MATTOS E (2009) Nidificaciónde aves de pastizal en el Parque Provincial E.Tornquist. Pp. 457–472 en:

[19] CAZZANIGA NJ Y ARELO-VICH HM (eds) Ambientes y recursos naturales del sud-oeste bonaerense: producción, contaminación y conser-vación. Editorial de la Universidad Nacional del Sur,Bahía Blanca

[20] DAVISON WB Y BOLLINGER E (2000) Predation rates onreal and artificial nests of grassland birds. Auk117:147–153

[21] DI GIACOMO AS (2005) Áreas importantes para la conser-vación de las aves en Argentina. Sitios prioritarios parala conservación de la biodiversidad. Aves Argentinas/Asociación Ornitológica del Plata, Buenos Aires

[22] DION N, HOBSON KA Y LARIVIÈRE S (2000) Interactiveeffects of vegetation and predators on the successof natural and simulated nests of grassland song-birds. Condor 102:629–634

[23] DONOVAN TM, JONES PW, ANNAND EM Y THOMPSONFR III (1997) Variation in local scale edge effects:mechanisms and landscape context. Ecology78:2064–2075

[24] ERIKSSON LM, EDENIUS L, ARESKOUG V Y MERITT DA JR(2001) Nest-predation at the edge: an experimentalstudy contrasting two types of edges in the dryChaco, Paraguay. Ecography 24:742–750

[25] FRANÇA LF Y MARINI MÂ (2009) Teste do efeito deborda na predação de ninhos naturais e artificiaisno cerrado do Planalto Central, Brasil. RevistaBrasileira de Zoologia 26:241–250

[26] FRANÇA LF, SOUSA NOM, DOS SANTOS LR, DUCA C,GRESSLER DT, BORGES FJA, LOPES LE, MANICA LT,PAIVA LV, DE MEDEIROS RCS Y MARINI MÂ (2009)Passeriformes: nest predators and prey in a Neo-tropical savanna. Revista Brasileira de Zoologia26:799–802

[27] GABELLI FM, FERNÁNDEZ GJ, FERRETTI V, POSSE G,COCONIER E, GAVIEIRO HJ, LLAMBÍAS PE, PELÁEZ PI,VALLÉS ML Y TUBARO PL (2004) Range contractionin the pampas meadowlark Sturnella defilippii in thesouthern pampas grasslands of Argentina. Oryx38:164–170

[28] GATES JE Y GYSEL LW (1978) Avian nest dispersion andfledging success in field-forest ecotones. Ecology59:871–873

[29] GITHIRU M, LENS L Y CRESSWELL W (2005) Nest preda-tion in a fragmented Afrotropical forest: evidencefrom natural and artificial nests. Biological Conser-vation 123:189–196

[30] HASKELL DG (1995) Forest fragmentation and nestpredation: are experiments with Japanese Quaileggs misleading? Auk 112:767–770

[31] HERNANDEZ F, ROLLINS D Y CANTU R (1997) Evaluat-ing evidence to identify ground-nesting preda-tors in west Texas. Wildlife Society Bulletin25:826–831

[32] KOZMA JM Y MATHEWS NE (1997) Breeding birdcommunities and nest plant selection in Chihua-huan desert habitats in South-Central New Mexico.Wilson Bulletin 109:424–436

[33] LARIVIÈRE S Y MESSIER F (1998) Effect of density andnearest neighbours on simulated waterfowl nests:can predators recognize high-density nestingpatches? Oikos 83:12–20

[34] LEGENDRE P Y LEGENDRE L (1998) Numerical ecology.Segunda edición. Elsevier, Amsterdam

[35] LOYDI A, DISTEL RA Y ZALBA SM (2010) Large herbivoregrazing and non-native plant invasions in montanegrasslands of central Argentina. Natural Areas Jour-nal 30:148–155

[36] LOYDI A Y ZALBA SM (2009) Feral horses dung piles asinvasion windows in natural grasslands. PlantEcology 201:471–480

[37] LUENGOS VIDAL EM (2003) Estudio comparado demetodologías de captura y de estimación de las poblacio-nes de zorro pampeano: Pseudalopex gymnocercus. Tesisde magister, Universidad Nacional del Sur, BahíaBlanca

[38] MAHAN HD (1956) Nocturnal predation on SongSparrow eggs by Milk Snake. Wilson Bulletin 68:245

[39] MAIER TJ Y DEGRAAF RM (2000) Predation on Japanesequail vs. House sparrow eggs in artificial nests: smalleggs reveal small predators. Condor 102:325–332

[40] MAJOR RE Y KENDAL CE (1996) The contribution ofartificial nest experiments to understanding avianreproductive success: a review of methods andconclusions. Ibis 138:298–307

[41] MARINI MÂ Y MELO C (1998) Predators of quail eggs,and the evidence of the remains: implications fornest predation studies. Condor 100:395–399

[42] MARTIN TE (1987) Food as a limit on breeding birds: alife-history perspective. Annual Review of Ecology andSystematics 18:453–487

[43] MARTIN TE (1993) Nest predation and nest sites. Newperspectives on old patterns. BioScience 43:523–532

[44] MARTIN TE Y LI P (1992) Life history traits of open- vs.cavity-nesting birds. Ecology 73:579–592

[45] MEZQUIDA ET Y MARONE L (2002) Microhabitat struc-ture and avian nest predation risk in an openArgentinean woodland: an experimental study. ActaOecologica 23:313–320

[46] MEZQUIDA ET Y MARONE L (2003) Are results of artifi-cial nest experiments a valid indicator of success ofnatural nests? Wilson Bulletin 115:270–276

[47] MOORE RP Y ROBINSON WD (2004) Artificial bird nests,external validity, and bias in ecological field stud-ies. Ecology 85:1562–1567

[48] MULLIN SJ Y COOPER RJ (1998) The foraging ecologyof the Gray Rat Snake (Elaphe obsoleta spiloides) —visual stimuli facilitate location of arboreal prey.American Midland Naturalist 140:397–401

[49] MURPHY MT (2003) Avian population trends withinthe evolving agricultural landscape of eastern andcentral United States. Auk 120:20–34

[50] NACK JL (2002) Effects of predators and cattle on ground-nesting grassland birds in southwestern Wisconsin pastures.Tesis de maestría, University of Wisconsin, Madison

[51] NACK JL Y RIBIC CA (2005) Apparent predation bycattle at grassland bird nests. Wilson Bulletin117:56–62

[52] ORTEGA CP, ORTEGA JC, RAPP CA Y BACKENSTO SA(1998) Validating the use of artificial nests in preda-tion experiments. Journal of Wildlife Management62:925–932

[53] PÄRT T Y WRETENBERG J (2002) Do artificial nests revealrelative nest predation risk on real nests? Journal ofAvian Biology 33:39–46

[54] PATON P (1994) The effect of edge on avian nestsuccess how strong is the evidence? ConservationBiology 8:17–26

[55] DELA PEÑA MR (2005) Reproducción de las aves argenti-nas (con descripción de pichones). LOLA, Buenos Aires

[56] RENFREW RB Y RIBIC CA (2003) Grassland passerinenest predators near pasture edges identified onvideotape. Auk 120:371–383

[57] RENFREW RB, RIBIC CA Y NACK JL (2005) Edge avoid-ance by nesting grassland birds: a futile strategy ina fragmented landscape. Auk 122:618–636

[58] RICKLEFS RE (1969) An analysis of nesting mortalityin birds. Smithsonian Contributions to Zoology 9:1–48

[59] ROBINSON WD, STYRSKY JN Y BRAWN JD (2005) Areartificial bird nests effective surrogates for estima-ting predation on real bird nests? A test with tropicalbirds. Auk 122:843–852

[60] SCHMIDT KA, GOHEEN JR, NAUMANN R, OSTFELD RS,SCHAUBER EM Y BERKOWITZ A (2001) Experimentalremoval of strong and weak predators: mice andchipmunks preying on songbird nests. Ecology82:2927–2936

[61] SCOROLLI AL Y LÓPEZ CAZORLA AC (2010) Demo-graphy of feral horses (Equus caballus): a long-termstudy in Tornquist Park, Argentina. Wildlife Research37:207–214

[62] SKAGEN SK, STANLEY TR Y DILLON MB (1999) Domammalian nest predators follow human scenttrails in the shortgrass prairie? Wilson Bulletin111:415–420

[63] SVAGELJ WS, MERMOZ ME Y FERNÁNDEZ GJ (2003) Effectof egg type on the estimation of nest predation inpasserines. Journal of Field Ornithology 74:243–249

[64] THOMPSON FR III Y BURHANS DE (2004) Differences inpredators of artificial and real songbird nests:evidence of bias in artificial nest studies. Conserva-tion Biology 18:373–380

[65] THOMPSON FR III, DIJAK W Y BURHANS DE (1999) Videoidentification of predators at songbird nests in oldfields. Auk 116:259–264VANDER HAEGEN WM, SCHROEDER MA Y DEGRAAF RM(2002) Predation on real and artificial nests inshrubsteppe landscapes fragmented by agriculture.Condor 104:496–506

[66] VICKERY PD, TUBARO PL, DA SILVA JMC, PETERJOHN BG,HERKERT JR Y CAVALCANTI RB (1999) Conservationof grassland birds in the Western Hemisphere.Studies in Avian Biology 19:2–26

[67] DE VILLALOBOS AE Y ZALBA SM (2010) Continuous feralhorses grazing and grazing exclusion in mountainpampean grasslands in Argentina. Acta Oecologica36:514–519

[68] WEATHERHEAD PJ Y BLOUIN-DEMERS G (2004) Under-standing avian nest predation: why ornithologistsshould study snakes. Journal of Avian Biology35:185–190

[69] WILLEBRAND T Y MARCSTRÖM V (1988) On the dangerof using dummy nests to study predation. Auk105:378–379

[70] WILLSON M, MORRISON JL, SIEVING KE, DE SANTO TL,SANTISTEBAN L Y DÍAZ I (2001) Patterns of predationrisk and survival of birds nests in a Chilean agricul-tural landscape. Conservation Biology 15:447–456

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