PDF - Revista Chilena de Historia Natural
Contents
1. garleppi in the study area because these birds run long distances at great speed their plumage color al lows them to mimic the environment and the topog raphy of the area is irregular Therefore we decided to use the fecal count technique as an indirect method for estimating population density Ojasti and Dallmeier 2000 This method has been used effectively in other studies on wild populations of rheas Bazzano et al 2002 Herrera et al 2004 Kusch and Henr quez 2011 Six samplings were conducted between 2011 and 2012 September and November 2011 March April July and November 2012 In each sampling 20 randomized tran sects were spaced at least 400 m apart This randomized design ensured sample independence allowing us to consider each transect as true replicates by avoiding repetition of a single transect in successive monthly samplings Transects of 500 m long were walked by a single observer in search of feces The exact perpendicu lar distance from the path to each encountered feces was measured with metric tape by an assistant Thus the observer never left the transect avoiding the record of additional feces All encountered feces were collected to avoid double counting Density of R p garleppi was calculated monthly using Distance 6 0 software Thomas et al 2009 which requires entering data on individuals defecation rate and feces permanence in the study area Buckland et al 2001 As we did not have defecation ra2. Agr cola y Ganadero SAG 2002 Navarro et al 1999 Secretar a de Ambiente y Desarrollo de la Naci n SAyDS 2000 Novaro et al 2000 Barri et al 2009b In Argentina in general R p garleppi would occur at lower densities than R p pennata which could be related to the primary produc tivity of the ecosystems Specifically the subspecies R p garleppi is distributed throughout the Puna ecoregion where the low biomass production in the environ ment determines a lower carrying capacity By con trast the Argentine Patagonia where R p pennata occurs comprises a wider range of environments the Monte and the Patagonia phytogeographic provinces the Monte Patagonia ecotone as well as mallines patch ily distributed wetland areas which provide habitat this ratite with important food resources Oesterheld et al 1998 Bellis et al 2006 Guevara et al 2006 Bianchi and Bravo 2008 This work provides the highest density record for R p garleppi so far and highlights changes in population size related to the characteristics of the life history of rheas and human factors that negatively affect the survival of wild populations Competing interests The authors declare that they have no competing interests Authors contributions NVM designed the study collected the data carried out the statistical analysis and drafted the manuscript RCO contributed to data acquisition and drafted the manuscript JLN participated in the a
3. Conserv 45 81 91 Cajal JL 1998 Una especie fr gil el and petizo bases para la conservaci n y anejo de la Puna y Cordillera Frontal de Argentina In Cajal J Tecchi R eds El rol de las Reservas de Biosfera UNESCO Uruguay Cappa F Borghi CE Campos VE Andino N Reus ML Giannoni SM 2014 Guanacos in the Desert Puna a trade off between drinking and the risk of being predated J Arid Environ 107 34 40 Carro M Fernandez G 2008 Seasonal variation in social organization and diurnal activity budget of the Greater Rhea Rhea americana in the Argentinean pampas Emu 108 2 167 173 Chebez J 2008 Los que se van Individuos Ed Albatros Buenos Aires Argentina CITES 2014 Convention on international trade in endangered species of wild fauna and flora www cites org Acceso 2 July 2014 Delsuc F Superina M Ferraris G Tilak M Douzeri EJ 2007 Molecular evidence for hybridization between the two living species of South American ratites potential conservation implications Conserv Genet 8 503 507 Di Rienzo JA 2011 Modelos lineales mixtos aplicaciones en InfoStat JA Di Rienzo RE Macchiavelli F Casanoves 1a Grupo Infostat C rdoba Di Rienzo JA Casanoves F Balzarini MG Gonzalez L Tablada M Robledo CW 2014 InfoStat versi n 2014 Grupo InfoStat FCA Universidad Nacional de C rdoba Argentina URL http www infostat com ar Page 5 of 5 Folch A 1992 Order Struthioni
4. away from the reserve and below 2 500 m a s l NVM personal observation where the habitat is domi nated by an open shrubland of L divaricata M rquez 1999 Indeed reproductive groups of males with females males with chicks and juveniles have been observed in this environment adjacent to the reserve NV Marinero unpublished data We were not able to compare our results with wild populations from Bolivia because there are no studies published on the density of R p garleppi in that country despite the heavy use of this subspecies by local communi ties to the extent that wild populations may be decimated Balderrama 2009 Our density records of R p garleppi Figure 2 are higher than density values of R p tarapacensis present in different protected areas of Chile which vary between 0 002 ind km Isluga Volcano National Park 1995 S 68 49 27 W and 0 022 ind km National Monument Salar Surire Page 4 of 5 18 49 41 S 693 39 W Acu a et al 2008 However our estimations are lower than the values recorded for R p pennata in the Patagonia of Chile and Argentina with records of 8 ind km 50 46 S 74 6 W Ultima Esperanza Chile 2 93 ind km Santa Cruz Argentina 2 51 ind km Chubut Argentina 2 06 ind km and 1 55 ind km Rio Negro Argentina and 1 94 ind km Neuqu n Argentina although higher than in some areas of its northern distri bution in Neuqu n province Argentina Servicio
5. limit in the population size of R p garleppi could be due to the movements made by the individuals to the reserve in search of refuge from poaching and live stock production two activities that are more intensively conducted in the surrounding fields during the non breeding season of the subspecies garleppi Ordo ez 2006 This perception of a protected area as refuge from the surroundings has also been described for other native herbivores such as Lama guanicoe in the Monte arid ecoregion in Argentina Acebes et al 2010 Moreover abundance fell to 188 individuals 40 in November 2011 and 2012 Figure 2 This lower limit of population size corresponds to the breeding season of R p garleppi While there was a record of an orphan egg in September 2012 no nest was found despite the intensive search made inside the reserve This drop in the number of indi viduals may be related to the species nesting preferences since individuals tend to select sites with high shrub cover instead of pastures which favors concealment and pro tection against predators and severe climate conditions Bellis et al 2006 Barri et al 2009a These sites are scarce in the study area where shrub cover is only 16 and pas tures are 24 whereas the remaining cover corresponds to bare soil NV Marinero unpublished data Therefore it is likely that during the reproductive season R p gar leppi individuals move toward surrounding areas about 14 km
6. Marinero et al Revista Chilena de Historia Natural 2014 87 17 http www revchilhistnat com content 87 1 17 Revista Chilena de Historia Natural a SpringerOpen Journal SHORT REPORT Open Access Density and abundance of Rhea pennata garleppi Struthioniformes Rheidae in the Puna ecoregion of Argentina Nancy Ver nica Marinero Ricardo Omar Cortez Joaqu n Luis Navarro and M nica Beatriz Martella Abstract Background Rhea pennata is classified internationally as a near threatened species with the subspecies R p garleppi being listed as endangered Finding The aim of this study was to provide updated information on the density and abundance of R p garleppi in the southern Puna ecoregion of Argentina Density was estimated indirectly on the basis of monthly feces counts during 2011 and 2012 using line transect surveys Monthly abundance was calculated by multiplying the density of each month by the area of the reserve 400 km Population size range was calculated considering the average of the months with the highest abundance and density as the upper limit and the average of the months with the lowest abundance and density as the lower limit The population size of this subspecies varied between 300 individuals 60 with a density of 0 75 individuals km 0 15 during the non breeding season and 188 individuals 40 with a density of 0 47 individuals km 0 10 during the reproductive season Co
7. Wild populations of R p garleppi are found in low densities with severe fluctuations throughout the species distribution range and with a tendency to decrease or be come locally extinct in many cases Cajal 1988 Chebez 2008 In the Puna the main factors that negatively affect wild populations of this ratite are hunting for meat con sumption and egg harvesting as subsistence resources Barbar n 2004 Hernandez 2011 Another threat is the use by local people of by products such as feathers skin fat and bones Barbar n 2004 In this scenario and in order to ensure their long term conservation the subspe cies R p garleppi is considered at risk of extinction CITES 2014 and R pennata has been categorized as near threatened IUCN 2014 However the lack of know ledge regarding the current status of wild populations of R p garleppi hinders the conservation of this subspecies The aim of this study was to provide updated information on the density and abundance of R p garleppi in the southern Puna ecoregion of Argentina 2014 Marinero et al licensee Springer This is an Open Access article distributed under the terms of the Creative Commons Attribution License http creativecommons org licenses by 4 0 which permits unrestricted use distribution and reproduction in any medium provided the original work is properly credited Marinero et al Revista Chilena de Historia Natural 2014 87 17 http www revchilhistnat com
8. abundance was performed using the Fisher s least significant difference LSD test when differences were significant at P lt 0 05 Balzarini et al 2008 Data were Logjp transformed for normalization of residuals Non transformed data were expressed as mean standard error of the mean Statistical analyses were performed using Infostat Di Rienzo et al 2014 Population size of the subspecies R p garleppi pre sented significant variations among months F 5 84 3 61 P 0 002 The upper limit of the population was 0 75 ind km 0 15 and was recorded in March April and July 2012 P lt 0 05 Figure 2 This density is the highest published until now but close to other records obtained in Argentina 0 67 ind km 29 25 60 S 66 50 60 W La Rioja and 0 52 ind km in Laguna de Pozuelo Biosphere Reserve 22 28 S 66 02 W Jujuy Cajal 1988 Cajal 1998 and references therein The differences in density esti mates might be due to the different methods used consid ering that Cajal 1988 states that the use of a motor vehicle to conduct the surveys of R p garleppi might have led to density underestimation By contrast we used the line transect method and fit a detection function of probability of signs which decreases with distance to the observer This method reduces the potential bias of the density estimator Buckland et al 2001 and provides a more realistic value of a population s density and abun dance in a giv
9. content 87 1 17 This study was conducted in Don Carmelo Private Re serve 400 km located on the Andean Precordillera of San Juan province in Argentina 30 56 52 S 69 05 02 W 3 100 m a s l The Reserve is located in the Argen tine Puna ecoregion in the southeastern border of the Altiplano in the central Andes Bonaparte 1978 The climate is arid and cold with intense solar radiation strong winds and daily temperature fluctuations that may exceed 30 C Reboratti 2006 Precipitations are scarce and occur between November and February de creasing to the west and south of the Puna Cabrera and Willink 1973 The reserve is located in the subregion known as dry Puna due to the lack of permanent rivers and lakes Cabrera 1976 The dominant habitat is the shrub steppe with a mean altitude of 13 9 cm 0 72 and the vegetation is xerophilous with 88 of bare soil Cappa et al 2014 Wild populations of R p garleppi inhabiting similar environments use indistinctly both the grassland plains of Stipa spp and low shrublands of Adesmia spp as well as the rocky and non rocky mountain slopes with shrubs of Lycium spp and Adesmia spp and low cover of Stipa spp Cajal 1998 Don Carmelo Private Reserve is a suitable site for the subspecies garleppi because it is not fragmented or disturbed by mining or agricultural activ ities and massive tourism is banned It is difficult to perform direct observation or monitor ing of R p
10. d 21 March 2014 Accepted 10 July 2014 Published online 04 September 2014 References Acebes P Traba J Malo JE Ovejero R Borghi CE 2010 Density and habitat use at different spatial scales of a guanaco population Lama guanicoe in the Monte Argentina Mammalia 74 57 62 Acu a MP Estades CM Gonz les BP Hern ndez JP Vukasovic MF Villase or NP 2008 Evaluaci n poblacional del suri Rhea pennata tarapacensis en las regiones de Arica Parinacota y de Tarapaca Informe Final CONAF Chile Balderrama JA 2009 Libro rojo de la fauna silvestre de vertebrados de Bolivia Ministerio de Medio Ambiente y Agua La Paz Balzarini MG Gonzalez L Tablada M Casanoves F Di Rienzo JA Robledo CW 2008 Manual del Usuario Editorial Brujas Cordoba Argentina Barbar n F 2004 Usos m gicos medicinales y rituales de la fauna en la Puna del oroeste Argentino y Sur de Bolivia Contribuciones al Manejo de Vida Silvestre en Latinoam rica 1 1 1 26 Barri FR Martella MB Navarro JL 2009a Reproductive success of wild Lesser Rheas Pterocnemia Rhea pennata pennata in north western Patagonia Argentina J Ornithol 150 511 514 Barri FR Martella MB Navarro JL 2009b Nest site habitat selection by Lesser Rheas Rhea pennata pennata in northwestern Patagonia Argentina J Ornithol 150 511 514 Bazzano G Martella MB Navarro J Bruera N Corbella C 2002 Uso de h bitat por el Nandu Rhea americana en un refugio de vida silvestre i
11. edia of Environmetrics 2 doi 10 1186 540693 014 0017 z Cite this article as Marinero et al Density and abundance of Rhea pennata garleppi Struthioniformes Rheidae in the Puna ecoregion of Argentina Revista Chilena de Historia Natural 2014 87 17
12. en area Thomas et al 2013 The lower limit of R p garleppi population density was 0 47 ind km 0 10 in November 2011 and 2012 P lt 0 05 Figure 2 Marinero et al Revista Chilena de Historia Natural 2014 87 17 http www revchilhistnat com content 87 1 17 Page 3 of 5 Detecci n probability 0 1 2 3 4 Perpendicular distance m Figure 1 Histogram of the perpendicular distance of feces of R p garleppi recorded at Don Carmelo Private Reserve San Juan Argentina The line represents the fit of the negative exponential function with cosine extension 5 6 7 8 9 10 Although this record is the lowest for our study popula tion it is still higher than records reported for other wild populations inhabiting Argentina and Per 0 41 ind km in Olaroz 23 43 S 66 48 W Jujuy Cajal 1998 and ref erences therein 0 12 ind km in Laguna Blanca Biosphere Reserve 26 28 S 66 48 W Catamarca 0 03 ind km in San Guillermo Biosphere Reserve 29 25 S 69 15 W San Juan and 0 01 ind km in Tacna 16 44 S 70 16 W Cajal 1988 Lleellish et al 2007 Taking into account the important wild population of the subspecies garleppi present in the study area it is necessary to promote its in situ conservation because it might become a source of individuals for possible recolonization and or reinforce ment of other populations undergoing higher conserva tion threat The higher abundance
13. formes In Del Hoyo J Elliot A Sargatal J eds Handbook of the birds of the world vol 1 Lynx Edicions Barcelona Fowler ME 1991 Comparative clinical anatomy of ratites J Zoo Wildlife Med 22 204 227 Guevara JC Bertiller MB Estevez OR Gr nwaldt EG Allegretti LI 2006 Pastizales y producci n animal en las zonas ridas de Argentina Science et changements plan taires S cheresse 17 245 256 Hanford PT MARES MA 1985 The mating systems of ratites and tinamous an evolutionary perspective Biol J Linn Soc 25 77 104 Hernandez JH 2011 Percepci n por parte de los pobladores en la zona de influencia de la reserva de Bi sfera San Guillermo San Juan acerca de aspectos relacionados con la fauna silvestres y su manejo Tesina de grado Universidad Nacional de San Juan San Juan Argentina Herrera LP Camparatore VM Laterra P 2004 Habitat relations of Rhea americana in an agroecosystem of Buenos Aires Province Argentina Biol Conserv 119 363 369 UCN 2014 Red list of threatened species www iucnredlist org accessed 2 July 2014 usch A Henriquez M 2011 Preferencias de habitat del Nandu Rhea pennata D Orbigny 1834 en matorrales intervenidos de Chile austral Anales Instituto Patagonia 39 1 43 50 Lleellish M Salinas L Chipana E 2007 Estado de conservaci n del Suri Pterocnemia pennata en el Per serie de publicaciones de flora y fauna silvestre Instituto Nacional de Recursos Naturales Lima rquez J 1999 Las reas protegida
14. mplicancias para a conservaci n y manejo de la especie Ornitol Neotrop 13 9 15 Bellis LM Navarro JL Vignolo PE Martella MB 2006 Habitat preferences of lesser rheas in Argentine Patagonia Biodivers Conserv 15 3065 3075 Bianchi AR Bravo GC 2008 Ecorregi n norandina Descripci n subregiones agroecosistemas sistemas productivos y cartograf a regional Ediciones INTA Salta Blake ER 1977 Manual of neotropical birds volumen 1 Spheniscidae to Laridae Chicago Univ Press Chicago Illinois Bonaparte J 1978 El mesozoico de Am rica del Sur y sus tetr podos Opera Lilloana 26 Universidad Nacional de Tucum n Fundaci n Miguel Lillo Tucum n Bonino N Bonvissuto G Pelliza Sbriller A Somlo R 1986 H bitos alimentarios de los herb voros en la zona central del rea ecol gica sierras y mesetas occidentales de Patagonia Revista Argentina de Producci n Animal 6 275 287 Buckland ST Anderson DR Burnham KP Laake JL Borchers DL Thomas L 2001 Introduction to distance sampling estimating abundance of biological population OXFORD University Press Great Britain Cabrera A 1976 Regiones fitogeogr ficas Argentinas Enciclopedia de agricultura y jardiner a Tomo ll Fasc culo 1 ACME Buenos Aires Cabrera A Willink A 1973 Biogeograf a de Am rica Latina Secretar a General de la Organizaci n de Estados Americanos Washington D C Cajal JL 1988 The Lesser Rhea in the Argentine Puna region present situation Biol
15. nalysis and interpretation of results and in writing the manuscript MBM conducted the fund raising participated in the design of the study the analysis and interpretation of results and in writing the manuscript All authors read and approved the final manuscript Authors information NVM is a fellow and JLN and MBM are researchers of the Consejo Nacional de Investigaciones Cientificas y T cnicas CONICET and teachers of the Universidad Nacional de C rdoba Acknowledgements We are grateful to Arturo Curatola for allowing us to carry out this research on Don Carmelo Private Reserve This work was funded by grants to MBM from the Secretar a de Ciencia y Tecnolog a de la Universidad Nacional de C rdoba SECyT UNC and the Agencia Nacional de Promoci n Cient fica y Tecnol gica de Argentina FONCyT We are grateful to the anonymous reviewers for their comments that helped improve a previous version of this manuscript Author details Instituto de Diversidad y Ecologia Animal Consejo Nacional de Investigaciones Cient ficas y T cnicas Universidad Nacional de C rdoba Marinero et al Revista Chilena de Historia Natural 2014 87 17 http www revchilhistnat com content 87 1 17 Centro de Zoologia Aplicada Universidad Nacional de Cordoba Rondeau 798 C rdoba X5000AVP Argentina Departamento de Biolog a Universidad Nacional de San Juan Argentina Av Ignacio de la Roza 590 Oeste San Juan 5000 Argentina Receive
16. nclusion This work shows the highest density record for R p garleppi so far and highlights changes in population size related to life history characteristics of rheas as well as human factors that negatively affect the survival of wild populations Keywords Rhea pennata garleppi Puna Conservation Andean precordillera Findings The family Rheidae is endemic to the Neotropics and com prises two species of large flightless birds Rhea americana and Rhea Pterocnemia pennata Blake 1977 R pennata includes three subspecies R p pennata present in south ern Chile and west central and southern Argentina in the Andean Precordillera steppes and Patagonian plateaus up to 2 000 m above sea level a s l R p tarapacensis which is distributed throughout northern Chile and R p gar leppi occurring in southern Peru southwestern Bolivia and northwestern Argentina The latter two subspecies inhabit open plains with grasslands shrublands and in the intermountain valleys of the Puna plateau above 3 500 m a s l Plenge 1982 Cajal 1988 Folch 1992 Correspondence veronicamarinero gmail com Instituto de Diversidad y Ecologia Animal Consejo Nacional de Investigaciones Cient ficas y T cnicas Universidad Nacional de C rdoba Centro de Zoolog a Aplicada Universidad Nacional de C rdoba Rondeau 798 C rdoba X5000AVP Argentina Full list of author information is available at the end of the article G Springer
17. on Carmelo Puna sanjuanina Tesina de licenciatura Univ Nacional de San Juan San Juan Argentina Plenge M 1982 The distribution of the lesser rhea Pterocnemia pennata in southern Per and northern Chile Ibis 124 168 172 Reboratti C 2006 Situaci n ambiental en las ecorregiones Puna y Altos Andes In Brown A Martinez U Acerbi M Corchera J eds La situaci n ambiental argentina 2005 Fundaci n Vida Silvestre Argentina Buenos Aires Sarasqueta DV 1990 Aspectos de la biolog a reproductiva del and petiso Pterocnemia pennata Comunicaci n t cnica N 1 INTA Secretar a de Ambiente y Desarrollo de la Naci n SAyDS 2000 Propuesta de enmienda para transferir Pterocnemia pennata pennata desde el Ap ndice al Ap ndice Il de CITES Jefatura de ministros Buenos Aires Argentina Servicio Agr cola y Ganadero SAG 2002 Propuesta de enmienda para transferir Pterocnemia pennata pennata desde el Ap ndice al Ap ndice Il de CITES XII Conferencia de las Partes de CITES Santiago Chile Thomas L Laake JL Rexstad E Strindberg S Marques FC Buckland S Borchers DL Anderson DR Burnham KP Burt ML Hedley SL Pollard JH Bishop JRB Marquez TA 2009 Distance 6 0 release 2 St Andrews Research Unit for Wildlife Population Assessment University of St Andrews Scotland http distancesampling org Distance index html Thomas L Buckland ST Burnham KP Anderson DR Laake JL Borchers DL Strindberg S 2013 Distance sampling Encyclop
18. s de la provincia de San Juan Multequina 8 1 10 artella MB Navarro JL Gonnet JM Monge SA 1996 Diet of greater rheas in an agroecosystem of central Argentina J Wildlife Manage 60 3 586 592 avarro JL Bellis LM L baque MC Martella MB 1998 Crecimiento de pichones de choiques en criaderos implicancias en el consumo y costos de alimentaci n conservaci n y manejo del choique en patagonia In Robles C Navarro J eds Ediciones 2000 INTA Bariloche Argentina avarro JL Cabrera MB Funes M Card n R Manero A 1999 Abundancia de Choiques en granjas de Patagonia In Informe a la Direcci n de Fauna y Flora Silvestres Secretar a de Recursos Naturales y Desarrollo Sustentable avarro JL Vignolo PE Demaria MR Maceira NO Martella MB 2005 Growth curves of farmed Greater Rheas Rhea americana albescens from central Argentina Archiv F r Gefl gelkunde 69 90 93 ovaro AJ Funes MC Walker R 2000 Ecological extinction of native prey of carnivore assemblage in Argentine Patagonia Biol Conserv 92 25 33 Oesterheld M Aguiar MR Paruelo JM 1998 Ecosistemas patag nicos Ecologia Austral 8 75 84 Ojasti J Dallmeier F 2000 Manejo de Fauna Silvestre Neotropical SI MAB Series 5 Smithsonian Institution MAB Biodiversity Program Washington D C Ordo ez C 2006 Uso del h bitat por Pterocnemia pennata e interacciones con herb voros silvestres Ctenomys y Lama guanicoe y dom sticos Equus caballus en la reserva privada de uso m ltiple D
19. te data for R p garleppi we used data from a similar Page 2 of 5 species R americana following Buckland et al 2001 These species are phylogenetically closely related Delsuc et al 2007 have similar body weight and size Fowler 1991 Navarro et al 1998 Navarro et al 2005 and exhibit a primarily herbivorous diet Bonino et al 1986 Martella et al 1996 The defecation rate used was 13 5 feces individual day 3 1 n 8 and the permanence time of the feces was 88 15 days 6 4 n 14 NV Mar inero personal observation To calculate monthly dens ity we used the negative exponential model with cosine extension Figure 1 The monthly abundance of R p garleppi was determined by multiplying density value of each month by the reserve area 400 km following Ojasti and Dallmeier 2000 Population size range of R p garleppi was calculated considering the average of months with highest density as the upper limit and the average of months with lowest density as the lower limit Abundance dependent variable as a function of months fixed effect was calculated using a heteroscedastic mixed model considering the sampling years 2011 and 2012 as random effect In addition given the heterosce dasticity of our data we indicated that error variance of abundance was different for each month grouping cri terion in the mixed model using the function Varldent Di Rienzo 2011 An a posteriori comparison of means of monthly
20. values of R p garleppi with 300 individuals 60 were recorded during March April and July 2012 P lt 0 05 Figure 2 The record of this upper limit in population size coincided with the occurrence of social groups of R p garleppi composed 3 6 aes 2 0 75 individuals km 0 15 300 individuals 60 3 2 Abundance Logyp April_2012 July_2012 o e N o 2 G gt Sampling months Figure 2 Variation of monthly abundance of R p garleppi in 2011 and 2012 in Don Carmelo Private Reserve San Juan Argentina Solid line upper limit of population size dashed line lower limit of population size Different letters indicate significant differences Fisher s LSD P lt 0 05 0 47 individuals km 0 10 eptember_2011 November_2011 November_2012 Marinero et al Revista Chilena de Historia Natural 2014 87 17 http www revchilhistnat com content 87 1 17 of juveniles females with juveniles and males in the reserve NVM pers obs this group composition is characteristic of the non reproductive season of rheas Hanford and Mares 1985 Sarasqueta 1990 Carro and Fernandez 2008 Thus the observed increase in popu lation size might be due to a reduction of aggressive behaviors among individuals during the non breeding season favoring the formation of groups of numerous individuals that tend to move together Sarasqueta 1990 However it is also very important to consider that the upper
Download Pdf Manuals
Related Search