Diets of plains vizcacha, greater rhea and cattle in Argentina Item Type text; Article Authors Pereira, J. A.; Quintana, R. D.; Monge, S. Citation Pereira, J. A., Quintana, R. D., & Monge, S. (2003). Diets of plains vizcacha, greater rhea and cattle in Argentina. Journal of Range Management, 56(1), 13-20. DOI 10.2307/4003875 Publisher Society for Range Management Journal Journal of Range Management Rights Copyright © Society for Range Management. Download date 30/09/2021 22:16:14 Item License http://rightsstatements.org/vocab/InC/1.0/ Version Final published version Link to Item http://hdl.handle.net/10150/643710 J. Range Manage. 56:13-20 January 2003 Diets of plains vizcacha, greater rhea and cattle in Argentina JAVIER A. PEREIRA, RUBEN D. QUINTANA, AND SUSANA MONGE Authors are Dissertation Student and Researcher and Laboratory Chief, Laboratorio de Ecologia Ambiental y Regional, Departamento de Ciencias Biologicas, FCEyN, Universidad de Buenos Aires. Ciudad Universitaria, Pabellon II, 1428 Buenos Aires, Argentina; and CONICET Technician, Instituto Argentino de Investigaciones de Zonas Aridas (IADIZA), CRICyT, CONICET. Calle Bajada del Cerro S/N, 5500 Mendoza, Argentina. At the time of the research, the senior author was Thallmann Visiting Scholar (UBA) and Research Associate, Dept. of Organismic and Evolutionary Biology, Harvard University, Cambridge, Mass. USA. Abstract Resumen Food habits of plains vizcacha (Lagostomus maximus), greater Se estudiaron los habitos alimenticios de la vizcacha rhea (Rhea americana) and cattle (Bos taurus) in the Parana (Lagostomus maximus), el iiandu (Rhea americana) y el ganado River Delta, Argentina, were studied over 2 years using micro- vacuno (Bos taurus) durante 2 anos en el Delta del Rio Parana, histological analysis of faeces. This was the first study of feeding Argentina, utilizando analysis microhistologico de heces. El pre- habits of these herbivores grazing in common in a wetland of sente es el primer estudio que focaliza en la comparacion de los Argentina. Poaceae was the main diet component throughout the habitos alimenticios de estos herbivoros en coexistencia en un year for all 3 herbivores, with the exception of spring and sum- area de humedal. Las poaceas fueron el componente principal en mer, when greater rhea consumed a higher proportion of la dieta de los 3 herbivoros a to largo del ano, excepto en primav- Prosopis nigra (Griseb.) pods. Botanical composition of plains era y verano, cuando los iiandues consumieron una mayor pro- vizcacha and cattle diets was generally similar for the same sea- porcion de vainas de Prosopis nigra (Griseb.). La composition son but different from that of greater rhea. Panicum milioides botanica de la dieta de la vizcacha y el ganado fue en general sim- Nees., Dichondra microcalyx (Hallier) Fabris. and P. nigra were ilar para una misma estacion pero diferente de la del nandu. the most consumed species for vizcacha, while P. nigra, Plantago Panicum milioides Nees., Dichondra microcalyx (Hallier) Fabris. y myosuros Lam., Solanum sp. L., Spilanthes stolonifera (H. et A.) P. nigra fueron las especies mas consumidas por la vizcacha, Baker and D. microcalyx dominated the greater rhea diet. The mientras que P. nigra, Plantago myosuros Lam., Solanum sp. L., species most consumed by cattle were Luziola peruviana Gmel. Spilanthes stolonifera (H. et A.) Baker y D. microcalyx dominaron and P. milioides. Similarities between the diets of plains vizcacha en la dieta del nandu. Las especies mas consumidas por el ganado and cattle seem to support the ranchers' view that vizcachas fueron Luziola peruviana Gmel. y P. milioides. La similitud entre compete with domestic herbivores for forage. However, high las dietas de la vizcacha y el ganado parecen apoyar la idea de los overlap in food habits would result in competition only if forage ganaderos sobre la competencia por el forraje entre estos her- is scarce. Greater rhea and cattle have different foraging pat- bivoros. Sin embargo, un elevado solapamiento dietario no se tra- terns and hunting of greater rhea is not justified solely on the duce en competencia a menos que el forraje resulte escaso. Por basis of forage competition with cattle. otra parte, el nandu y el ganado presentan diferentes patrones de forrajeo y la caceria que sufren estas ayes no esta justificada uni- camente sobre la base de la competencia por el forraje. Key Words: diet composition, herbivory, Lagostomus max- imus, Parana River Delta, Rhea americana tions (e.g., Bonino et al. 1986, Kufner and Pelliza 1987, Martella In farming ecosystems, cattle and other domestic species often et al. 1996, Quintana et al. 1998a, 1998b). co-exist with wildlife. Roughly 80% of Argentina is dedicated to Plains vizcacha (Lagostomus maximus) and greater rhea (Rhea extensive cattle ranching (CONAPA 1991) where cattle interact americana) are 2 native species found in these ecosystems. Plains with a large number of wild species that use the same resources. vizcacha are large nocturnal rodents of the Chinchillidae family However, few studies in Argentina have quantified these interac- that dwell in communal burrows ("vizcacheras") of grasslands and semi-arid scrublands from southern Paraguay and Bolivia to central Argentina (Llanos and Crespo 1952, Branch 1993). Greater rhea Research was funded by the TX-16 and PICT 98 N° 04503 grants of the UBACyT and the FONCYT programmes, respectively. The authors wish to thank also live in grasslands and bush country from Brazil and Bolivia to Mr. I. Schojett for allowing the study to be conducted on his ranch, D. Villareal for central Argentina. These birds live in polygamous social clusters his bibliography contribution and N. Madanes, M. Cagnoni, S. Arias, G. Aprile, N. and are generally associated with farming and cleared fields where Fracassi, D. Varela and F. Gagliardi for their field support. A special thanks to L. native vegetation has been replaced by improved pastures (Martella Azcoaga for her invaluable help with the English translation, Dr. 0. Solbrig for his al. support at Harvard University, and the anonymous reviewers for constructive criti- et 1996, Reboreda and Fernandez 1997). cism. The plains vizcacha is often considered to be an agricultural Manuscript accepted 14 May 02. pest, damaging soil and vegetation (Weir 1974) due to its burrow- JOURNAL OF RANGE MANAGEMENT 56(1) January 2003 13 ing and grazing habits and causing losses Soils are composed of a clayey, sodic (Holechek and Vavra 1981, Holechek et in yield of crops such as corn, soybean, horizon close to the surface. These sodic al. 1982). Frequencies of each consumed pastures, and horticultural species (Rendel clays hamper water penetration because item were converted to percentages of the 1990, Navarro et al. 1997). It is also hunt- they swell when wet, creating a layer that total sample weight (Holechek and Gross ed for its pelt (Rendel 1990, Bruggers and is effectively impermeable. Trampling by 1982, Martella et al. 1996). Zaccagnini 1994) and used as a food cattle compounds the problem by com- Composite samples of greater rhea under- resource by humans (Mares and Ojeda pressing and hardening the soil, and erod- went a special procedure; whole or frag- 1984). Hunting has severely reduced the ing thin layers of topsoil (Arias 2000). mented pods and seeds of P. nigra and numbers of plain vizcachas, and it is now Extensive cattle ranching (0.7 cows per arthropods were separated from the herba- extinct in large tracts of the wet Pampa hectare per year), hunting of wildlife ceous components and each of these 3 com- (Redford and Eisenberg 1992). Greater species for food and trade, and exploita- ponents was dried and weighed. Herbaceous rhea also have been hunted intensively for tion of P. nigra trees for lumber are the components were then analyzed following meat, feathers and skin, and was declared main human activities in this region. the technique described above. a harmful species due to its negative Vizcachas dig their burrows both in the The percent of each food item was cal- impact on crops (Bertonatti 1997) and grasslands and the forest patches and their culated for each season. Diet correlations potential competition with cattle for forage foraging is restricted to the areas sur- and dietary similarity among seasons and (Martella et al. 1996). rounding the burrows (Branch and Sosa among herbivore species were analyzed There have been few scientific studies 1994, Arias 2000). Greater rhea and cattle, using two-tailed Spearman's rank correla- on the feeding habits of these wild herbi- on the other hand, graze over extensive tion coefficients (Zar 1996) and vores despite their widespread continental areas, including, in the case of cattle, veg- Kulczynski's similarity index (Smith and distribution. Plains vizcacha are selective etation from the streams. Cattle were Shandruk 1979, Henley et al. 2001), grazers (Llanos and Crespo 1952) while always present on the study area and the respectively. Data were averaged for the 2 greater rhea feed on vegetable matter as overall level of forage utilization was years for plains vizcacha and cattle to well as arthropods and small vertebrates moderate. compare botanical composition of diets (Bruning 1974). Fresh faeces of plains vizcachas and among seasons and herbivores. This study focuses, for the first time, on cows were collected seasonally for 2 con- a wetland area of Argentina (the Parana secutive years, between November 1996 River Delta Region) and surveys the food (spring) and August 1998 (winter). Results habits of plains vizcachas, greater rheas Greater rhea fresh faeces were collected and cattle sharing the same grazing area. only in spring/summer 1997 and fall/win- While vizcachas and cattle fed exclu- ter 1998, when these birds were present on sively on plant leaves, greater rhea also the study area. Collection dates were in fed on P. nigra pods and consumed some Materials and Methods the middle of the respective season.