mariela borgnia | Universidad Nacional de Luján (original) (raw)
Papers by mariela borgnia
Se describe un dispositivo que permite evaluar simultáneamente varios parámetros conductuales de ... more Se describe un dispositivo que permite evaluar simultáneamente varios parámetros conductuales de peces en cautiverio. Se informan los resultados preliminares alcanzados al exponer juveniles (3-4 g) de la carpa común (Cyprinus carpio) a dos soluciones subletales de de Cd 2+ (0.3 y 0.5 mg/L), determinándose los cambios en su actividad natatoria (expresada cuantitativamente mediante un Indice de actividad relativa, I a ) y en sus preferencias altitudinal y lateral en los acuarios. La actividad natatoria total se redujo significativamente a la concentración más elevada del metal, retornando a los niveles basales registrados en el período Control luego de transferir los peces a medio sin el metal. La preferencia altitudinal, resultó modificada, encontrándose que los peces expuestos al metal se hallaban la mayor cantidad de tiempo en la capa superior de los acuarios. En cuanto a la preferencia lateral el resultado más importante fue la evidencia de que los mismos peces evitaban la sección correspondiente al sitio de goteo de la solución de Cadmio, sin hallarse un patrón particular de distribución en el resto de las secciones de los acuarios. Los cambios en la actividad natatoria total y en la preferencia altitudinal de los peces fueron reversibles; en cambio, la alteración en la preferencia lateral no se modificó luego del reemplazo de las soluciones de Cd por medios limpios.
Journal of Mammalogy
This study presents the first description of social behavior and structure in native populations ... more This study presents the first description of social behavior and structure in native populations of the coypu (Myocastor coypus). Data from behavioral observations and trapping were used to describe group composition and behavior at 3 study areas in east-central Argentina in 1999-2000. Seven groups were described (11 coypus/group Ϯ 1.5 SE). Groups were characterized by several adult and subadult females, 1 dominant male, several adult and subadult males, and a variable number of juveniles. Subgroups (mainly composed of juveniles and small adult males) were also identified within some groups. Group fidelity was relatively high. Amicable interactions and cooperative behaviors such as nursing in groups, allogrooming, and alarm calls occurred within groups. Agonistic interactions and marking behavior were rare but suggested that the largest male was socially dominant. This study confirms gregarious habits and a polygynous mating system for the species and provides the first report of the existence of some cooperative behaviors.
En este capítulo se analizan algunos aspectos de la ecología alimentaria de las vicuñas en su amb... more En este capítulo se analizan algunos aspectos de la ecología alimentaria de las vicuñas en su ambiente natural y bajo libre pastoreo. Se describe un estudio realizado en la puna seca catamarqueña con el objetivo general de aportar nuevos conocimientos al estudio de la dieta y al uso de indicadores de calidad nutricional en mamíferos herbívoros silvestres, tomando como modelo a esta especie en su ambiente típico. Los resultados muestran que a fines de la estación húmeda las estepas ofrecen una vegetación de mejor calidad que las vegas y representan un recurso de importancia para las vicuñas durante esta época del año. Las vicuñas obtuvieron en las estepas una dieta con una mayor concentración de proteínas que en las vegas, lo que indica que estos animales aprovechan, al menos en parte, la vegetación esteparia. Pero en general las especies vegetales citadas en la bibliografía como altamente consumidas por la vicuña no son las que presentaron la mayor concentración de proteínas en nuestros análisis de laboratorio, por lo resulta factible que otros factores actúen en la selección de la dieta de esta especie. En comparación con otros herbívoros de la zona, la vicuña obtuvo una dieta de calidad similar o superior en cuanto a contenido de proteínas, si bien son necesarios estudios comparativos sobre digestibilidad entre la vicuña y otras especies para obtener resultados concluyentes al respecto.
Ecologia Austral
La ardilla de vientre rojo en Argentina y el manejo de especies introducidas como un problema bio... more La ardilla de vientre rojo en Argentina y el manejo de especies introducidas como un problema biológico y social RESUMEN. El estudio y manejo de especies exóticas invasoras ha estado principalmente enfocado en conocer el proceso de invasión y técnicas adecuadas de manejo. Sin embargo, en los últimos años los estudios que promueven la participación de diferentes grupos sociales de la comunidad en los planes de manejo han cobrado importancia. En este trabajo describimos las opiniones y actitudes predominantes de seis grupos sociales (productores y prestadores de servicios, ambientalistas, vecinos, personal de áreas protegidas, funcionarios y docentes) con respecto a la presencia de la ardilla de vientre rojo introducida en Argentina. La existencia de varios focos de invasión de ardillas en tres provincias argentinas se relaciona con liberaciones intencionales de ardillas, en ocasiones obtenidas por comercio ilegal. Las opiniones con respecto a la presencia de ardillas variaron desde u...
Ecologia Austral
In this work we present the first characterization and classification of plant communities and ha... more In this work we present the first characterization and classification of plant communities and habitats in a typical area of the Argentinean Dry Puna sub-region, corresponding to Laguna Blanca (Catamarca, Argentina) Biosphere Reserve. A floristic list of 75 plant species was conducted. Six types of environments were characterized based on field work, satellite images using GIS: grass steppe, shrub steppe, mixed steppe, "vegas", "salt marsh" and "peladares". Three types of shrub steppes were recognized, based on dominant shrub: "rica-rical" (Acantholippia sp.), "tolillal alto" (Fabiana densa) and "tolillar bajo" (Fabiana spp.). Also three types of grass steppes were defined depending on dominant grass: Stipa spp., Festuca spp. and Panicum chloroleucum steppes. Two mixed steppes were described, based on grass species present: Stipa spp. and Panicum chloroleucum steppes. This classification was validated with Kappa index using...
Biological Invasions, 2015
ABSTRACT Arboreal squirrels of the Asiatic genus Callosciurus have shown high likelihood of estab... more ABSTRACT Arboreal squirrels of the Asiatic genus Callosciurus have shown high likelihood of establishment from few released animals, in particular, C. erythraeus has established wild populations in Argentina, Belgium, France, Hong Kong, Japan, and The Netherlands. We report the invasion process of C. erythraeus in Argentina in the last four decades and suggest management actions for each foci. Between February 2011 and November 2014 we conducted field surveys and interviews in nine sites in central Argentina to confirm the presence of C. erythraeus, describe their history of introduction, and estimate range expansion and squirrel relative abundance. We report a two decades lag-phase until the onset of translocations of C. erythraeus within national boundaries that resulted in a constant increase of the cumulative number of releases. We confirm nine new release events between 1995 and 2012 and six new invasion foci that yields a total of 13 deliberate releases and 10 invasion foci established in rural and urban areas of Argentina. Spread rate ranged from 0.12 to 0.66 km/year. An intermediate relative density of squirrels (2–7 ind/ha) was found close to release sites except in one case. All introduction events involved squirrels translocated from the first, 40 years old invasion focus, occasionally involving illegal trade. The rate of introduction events in the last decades and the translocation-lag phase described in this study should call the attention in all countries dealing with charismatic, introduced species. Translocation disruption requires urgent attention to slow down the invasion of this and other species.
Small Ruminant Research, 2010
Vicuña, Vicugna vicugna, is one of the few large native herbivores of South American and it is co... more Vicuña, Vicugna vicugna, is one of the few large native herbivores of South American and it is considered a keystone resource for the Andean Region. We studied foraging ecology of free ranging vicuñas at Laguna Blanca MAB-UNESCO Biosphere Reserve (Catamarca, Argentina), within dry Puna environment. Vicuñas showed a stable diet throughout the year, with marked differences at spatial scale. Diet of vicuñas included vegetation from all habitats, all vegetation strata and all functional groups of plants, suggesting that vicuñas can use a large range of plant species that are distributed in almost all portions of their range (they used 39 of 75 available plant species), behaving as a generalist ungulate. Vicuñas consumed large proportion of grasses (59-72%) and shrubs represented 16-19% of vicuña overall diet, reaching 45% at local sites, so we proposed that in this puna ecosystem vicuñas do not behave as strict grazers. Although vicuñas showed high diet plasticity, only two grasses, Panicum chloroleucum and Distichlis spp. represented nearly 50% of the diet. In relation to photosynthesis pathways of the plants, C 4 grasses contributed higher to proportions in diet than C 3 grasses. Vicuñas showed a selectivity foraging behaviour by consuming swamp forages, low and medium vegetation strata, and a few plant species in more proportion to their availability. Vicuñas did not eat plant species with more overall nutritional quality in higher proportion than species with less nutritional contents. However, the consumption of steppe grasses was in direct proportion to its crude protein content. This work brings a broad description of the foraging ecology of southern subspecies of vicuña, V. v. vicugna, by researching botanical composition and nutritional quality of the diet. These features of diet of vicuñas can be considered as part of its wide range of feeding responses to live in the poor environment of altiplano.
The Journal of Wildlife Management, 2000
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Journal of Mammalogy, 2003
This study presents the first description of social behavior and structure in native populations ... more This study presents the first description of social behavior and structure in native populations of the coypu (Myocastor coypus). Data from behavioral observations and trapping were used to describe group composition and behavior at 3 study areas in east-central Argentina in 1999-2000. Seven groups were described (11 coypus/group Ϯ 1.5 SE). Groups were characterized by several adult and subadult females, 1 dominant male, several adult and subadult males, and a variable number of juveniles. Subgroups (mainly composed of juveniles and small adult males) were also identified within some groups. Group fidelity was relatively high. Amicable interactions and cooperative behaviors such as nursing in groups, allogrooming, and alarm calls occurred within groups. Agonistic interactions and marking behavior were rare but suggested that the largest male was socially dominant. This study confirms gregarious habits and a polygynous mating system for the species and provides the first report of the existence of some cooperative behaviors.
Journal of Arid Environments, 2008
Isoleg theory predicts that coexistence between two competing species can occur when the subordin... more Isoleg theory predicts that coexistence between two competing species can occur when the subordinate, generalist species uses alternative patches of resources as the density of the dominant specialist species increases. These models provide a framework to determine if a native species is subordinate to an introduced one, thus requires conservation considerations. We investigated habitat interactions between a wild neotropical camelid and domestic exotic ungulates in the Andean Puna semi-desert of South America. The Puna or Altiplano is an arid environment located in high altitudes, with cold and dry weather, and two main types of habitats, steppes and swamp areas. There was a high overlap of diets between species. Vicuñ as were generalists in the use of habitat, but invested foraging effort in swamp habitats, while livestock were taken to swamp habitats by local people. Vicuñ as and livestock were spatially segregated. Vicuñ as used the preferred habitat less than expected from their foraging preference. We concluded that vicuñ as and livestock coexist because vicuñ as occupy sub-optimal habitats whilst livestock concentrate in the richest ones. Vicuñ as can deal with poor habitats because they have several adaptations to live in deserts.
Acta Oecologica, 2003
Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously p... more Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously proposed to explain the species' preference for aquatic plants. First, the nutritional benefit hypothesis which states that aquatic plants are more nutritional than terrestrial plants. Second, the behavioural trade-off hypothesis which states that coypus avoid foraging far from the water because of the costs associated with other types of behaviour. In order to test the nutritional benefit hypothesis, we studied the diet composition of coypus in relation to the protein content of the diet and of the plants available in the environment. Fieldwork was conducted seasonally from November 1999 to August 2000 at one study site located in the Province of Buenos Aires, east central Argentina. Behavioural observations showed that coypus remained foraging in the water and microhistological analysis of faeces indicated that their diet was principally composed of hygrophilic monocotyledons (Lemna spp. and Eleocharis spp.) throughout the year. We did not find support for the nutritional benefit hypothesis: nutritional quality (based on nitrogen content) of hygrophilic plants was not higher than that of terrestrial plants, and seasonal changes in diet quality did not match either fluctuations in vegetation quality or proportion of hygrophilic plants in the diet. Although not directly tested, the behavioural trade-off hypothesis may explain why coypus prefer to forage in or near the water as a mechanism for reducing predation risk. a We included the pteridophyte Azolla within the group of hygrophilic monocotyledons.
Ecologia Austral
RESUMEN. En este trabajo presentamos la primera caracterización y clasificación con imágenes de l... more RESUMEN. En este trabajo presentamos la primera caracterización y clasificación con imágenes de los ambientes y la vegetación en un área típica de la Puna seca argentina, correspondiente a la Reserva de Biósfera Laguna Blanca (Catamarca, Argentina). Se realizó un relevamiento florístico del lugar identificando 75 especies. Se describieron y se mapearon seis tipos de ambientes utilizando técnicas de Sistemas de Información Geográfica: estepas arbustivas, estepas graminosas, estepas mixtas, vegas, salinas y peladares. Dentro de las estepas arbustivas se reconocieron tres tipos, dependiendo de la especie de arbusto dominante: rica-rical (Acantholippia sp.), tolillar alto (Fabiana densa) y tolillar bajo (Fabiana spp. valle, asociándose estos patrones a los tipos de vegetación y los ambientes. Esta caracterización y mapeo permitió la comparación con otras zonas de puna y en particular, aportó información básica para el manejo de la Reserva. [Palabras clave: Puna, áreas protegidas, releva...
Se describe un dispositivo que permite evaluar simultáneamente varios parámetros conductuales de ... more Se describe un dispositivo que permite evaluar simultáneamente varios parámetros conductuales de peces en cautiverio. Se informan los resultados preliminares alcanzados al exponer juveniles (3-4 g) de la carpa común (Cyprinus carpio) a dos soluciones subletales de de Cd 2+ (0.3 y 0.5 mg/L), determinándose los cambios en su actividad natatoria (expresada cuantitativamente mediante un Indice de actividad relativa, I a ) y en sus preferencias altitudinal y lateral en los acuarios. La actividad natatoria total se redujo significativamente a la concentración más elevada del metal, retornando a los niveles basales registrados en el período Control luego de transferir los peces a medio sin el metal. La preferencia altitudinal, resultó modificada, encontrándose que los peces expuestos al metal se hallaban la mayor cantidad de tiempo en la capa superior de los acuarios. En cuanto a la preferencia lateral el resultado más importante fue la evidencia de que los mismos peces evitaban la sección correspondiente al sitio de goteo de la solución de Cadmio, sin hallarse un patrón particular de distribución en el resto de las secciones de los acuarios. Los cambios en la actividad natatoria total y en la preferencia altitudinal de los peces fueron reversibles; en cambio, la alteración en la preferencia lateral no se modificó luego del reemplazo de las soluciones de Cd por medios limpios.
Journal of Mammalogy
This study presents the first description of social behavior and structure in native populations ... more This study presents the first description of social behavior and structure in native populations of the coypu (Myocastor coypus). Data from behavioral observations and trapping were used to describe group composition and behavior at 3 study areas in east-central Argentina in 1999-2000. Seven groups were described (11 coypus/group Ϯ 1.5 SE). Groups were characterized by several adult and subadult females, 1 dominant male, several adult and subadult males, and a variable number of juveniles. Subgroups (mainly composed of juveniles and small adult males) were also identified within some groups. Group fidelity was relatively high. Amicable interactions and cooperative behaviors such as nursing in groups, allogrooming, and alarm calls occurred within groups. Agonistic interactions and marking behavior were rare but suggested that the largest male was socially dominant. This study confirms gregarious habits and a polygynous mating system for the species and provides the first report of the existence of some cooperative behaviors.
En este capítulo se analizan algunos aspectos de la ecología alimentaria de las vicuñas en su amb... more En este capítulo se analizan algunos aspectos de la ecología alimentaria de las vicuñas en su ambiente natural y bajo libre pastoreo. Se describe un estudio realizado en la puna seca catamarqueña con el objetivo general de aportar nuevos conocimientos al estudio de la dieta y al uso de indicadores de calidad nutricional en mamíferos herbívoros silvestres, tomando como modelo a esta especie en su ambiente típico. Los resultados muestran que a fines de la estación húmeda las estepas ofrecen una vegetación de mejor calidad que las vegas y representan un recurso de importancia para las vicuñas durante esta época del año. Las vicuñas obtuvieron en las estepas una dieta con una mayor concentración de proteínas que en las vegas, lo que indica que estos animales aprovechan, al menos en parte, la vegetación esteparia. Pero en general las especies vegetales citadas en la bibliografía como altamente consumidas por la vicuña no son las que presentaron la mayor concentración de proteínas en nuestros análisis de laboratorio, por lo resulta factible que otros factores actúen en la selección de la dieta de esta especie. En comparación con otros herbívoros de la zona, la vicuña obtuvo una dieta de calidad similar o superior en cuanto a contenido de proteínas, si bien son necesarios estudios comparativos sobre digestibilidad entre la vicuña y otras especies para obtener resultados concluyentes al respecto.
Ecologia Austral
La ardilla de vientre rojo en Argentina y el manejo de especies introducidas como un problema bio... more La ardilla de vientre rojo en Argentina y el manejo de especies introducidas como un problema biológico y social RESUMEN. El estudio y manejo de especies exóticas invasoras ha estado principalmente enfocado en conocer el proceso de invasión y técnicas adecuadas de manejo. Sin embargo, en los últimos años los estudios que promueven la participación de diferentes grupos sociales de la comunidad en los planes de manejo han cobrado importancia. En este trabajo describimos las opiniones y actitudes predominantes de seis grupos sociales (productores y prestadores de servicios, ambientalistas, vecinos, personal de áreas protegidas, funcionarios y docentes) con respecto a la presencia de la ardilla de vientre rojo introducida en Argentina. La existencia de varios focos de invasión de ardillas en tres provincias argentinas se relaciona con liberaciones intencionales de ardillas, en ocasiones obtenidas por comercio ilegal. Las opiniones con respecto a la presencia de ardillas variaron desde u...
Ecologia Austral
In this work we present the first characterization and classification of plant communities and ha... more In this work we present the first characterization and classification of plant communities and habitats in a typical area of the Argentinean Dry Puna sub-region, corresponding to Laguna Blanca (Catamarca, Argentina) Biosphere Reserve. A floristic list of 75 plant species was conducted. Six types of environments were characterized based on field work, satellite images using GIS: grass steppe, shrub steppe, mixed steppe, "vegas", "salt marsh" and "peladares". Three types of shrub steppes were recognized, based on dominant shrub: "rica-rical" (Acantholippia sp.), "tolillal alto" (Fabiana densa) and "tolillar bajo" (Fabiana spp.). Also three types of grass steppes were defined depending on dominant grass: Stipa spp., Festuca spp. and Panicum chloroleucum steppes. Two mixed steppes were described, based on grass species present: Stipa spp. and Panicum chloroleucum steppes. This classification was validated with Kappa index using...
Biological Invasions, 2015
ABSTRACT Arboreal squirrels of the Asiatic genus Callosciurus have shown high likelihood of estab... more ABSTRACT Arboreal squirrels of the Asiatic genus Callosciurus have shown high likelihood of establishment from few released animals, in particular, C. erythraeus has established wild populations in Argentina, Belgium, France, Hong Kong, Japan, and The Netherlands. We report the invasion process of C. erythraeus in Argentina in the last four decades and suggest management actions for each foci. Between February 2011 and November 2014 we conducted field surveys and interviews in nine sites in central Argentina to confirm the presence of C. erythraeus, describe their history of introduction, and estimate range expansion and squirrel relative abundance. We report a two decades lag-phase until the onset of translocations of C. erythraeus within national boundaries that resulted in a constant increase of the cumulative number of releases. We confirm nine new release events between 1995 and 2012 and six new invasion foci that yields a total of 13 deliberate releases and 10 invasion foci established in rural and urban areas of Argentina. Spread rate ranged from 0.12 to 0.66 km/year. An intermediate relative density of squirrels (2–7 ind/ha) was found close to release sites except in one case. All introduction events involved squirrels translocated from the first, 40 years old invasion focus, occasionally involving illegal trade. The rate of introduction events in the last decades and the translocation-lag phase described in this study should call the attention in all countries dealing with charismatic, introduced species. Translocation disruption requires urgent attention to slow down the invasion of this and other species.
Small Ruminant Research, 2010
Vicuña, Vicugna vicugna, is one of the few large native herbivores of South American and it is co... more Vicuña, Vicugna vicugna, is one of the few large native herbivores of South American and it is considered a keystone resource for the Andean Region. We studied foraging ecology of free ranging vicuñas at Laguna Blanca MAB-UNESCO Biosphere Reserve (Catamarca, Argentina), within dry Puna environment. Vicuñas showed a stable diet throughout the year, with marked differences at spatial scale. Diet of vicuñas included vegetation from all habitats, all vegetation strata and all functional groups of plants, suggesting that vicuñas can use a large range of plant species that are distributed in almost all portions of their range (they used 39 of 75 available plant species), behaving as a generalist ungulate. Vicuñas consumed large proportion of grasses (59-72%) and shrubs represented 16-19% of vicuña overall diet, reaching 45% at local sites, so we proposed that in this puna ecosystem vicuñas do not behave as strict grazers. Although vicuñas showed high diet plasticity, only two grasses, Panicum chloroleucum and Distichlis spp. represented nearly 50% of the diet. In relation to photosynthesis pathways of the plants, C 4 grasses contributed higher to proportions in diet than C 3 grasses. Vicuñas showed a selectivity foraging behaviour by consuming swamp forages, low and medium vegetation strata, and a few plant species in more proportion to their availability. Vicuñas did not eat plant species with more overall nutritional quality in higher proportion than species with less nutritional contents. However, the consumption of steppe grasses was in direct proportion to its crude protein content. This work brings a broad description of the foraging ecology of southern subspecies of vicuña, V. v. vicugna, by researching botanical composition and nutritional quality of the diet. These features of diet of vicuñas can be considered as part of its wide range of feeding responses to live in the poor environment of altiplano.
The Journal of Wildlife Management, 2000
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.
Journal of Mammalogy, 2003
This study presents the first description of social behavior and structure in native populations ... more This study presents the first description of social behavior and structure in native populations of the coypu (Myocastor coypus). Data from behavioral observations and trapping were used to describe group composition and behavior at 3 study areas in east-central Argentina in 1999-2000. Seven groups were described (11 coypus/group Ϯ 1.5 SE). Groups were characterized by several adult and subadult females, 1 dominant male, several adult and subadult males, and a variable number of juveniles. Subgroups (mainly composed of juveniles and small adult males) were also identified within some groups. Group fidelity was relatively high. Amicable interactions and cooperative behaviors such as nursing in groups, allogrooming, and alarm calls occurred within groups. Agonistic interactions and marking behavior were rare but suggested that the largest male was socially dominant. This study confirms gregarious habits and a polygynous mating system for the species and provides the first report of the existence of some cooperative behaviors.
Journal of Arid Environments, 2008
Isoleg theory predicts that coexistence between two competing species can occur when the subordin... more Isoleg theory predicts that coexistence between two competing species can occur when the subordinate, generalist species uses alternative patches of resources as the density of the dominant specialist species increases. These models provide a framework to determine if a native species is subordinate to an introduced one, thus requires conservation considerations. We investigated habitat interactions between a wild neotropical camelid and domestic exotic ungulates in the Andean Puna semi-desert of South America. The Puna or Altiplano is an arid environment located in high altitudes, with cold and dry weather, and two main types of habitats, steppes and swamp areas. There was a high overlap of diets between species. Vicuñ as were generalists in the use of habitat, but invested foraging effort in swamp habitats, while livestock were taken to swamp habitats by local people. Vicuñ as and livestock were spatially segregated. Vicuñ as used the preferred habitat less than expected from their foraging preference. We concluded that vicuñ as and livestock coexist because vicuñ as occupy sub-optimal habitats whilst livestock concentrate in the richest ones. Vicuñ as can deal with poor habitats because they have several adaptations to live in deserts.
Acta Oecologica, 2003
Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously p... more Foraging behaviour of wild coypu was studied to examine two hypotheses that had been previously proposed to explain the species' preference for aquatic plants. First, the nutritional benefit hypothesis which states that aquatic plants are more nutritional than terrestrial plants. Second, the behavioural trade-off hypothesis which states that coypus avoid foraging far from the water because of the costs associated with other types of behaviour. In order to test the nutritional benefit hypothesis, we studied the diet composition of coypus in relation to the protein content of the diet and of the plants available in the environment. Fieldwork was conducted seasonally from November 1999 to August 2000 at one study site located in the Province of Buenos Aires, east central Argentina. Behavioural observations showed that coypus remained foraging in the water and microhistological analysis of faeces indicated that their diet was principally composed of hygrophilic monocotyledons (Lemna spp. and Eleocharis spp.) throughout the year. We did not find support for the nutritional benefit hypothesis: nutritional quality (based on nitrogen content) of hygrophilic plants was not higher than that of terrestrial plants, and seasonal changes in diet quality did not match either fluctuations in vegetation quality or proportion of hygrophilic plants in the diet. Although not directly tested, the behavioural trade-off hypothesis may explain why coypus prefer to forage in or near the water as a mechanism for reducing predation risk. a We included the pteridophyte Azolla within the group of hygrophilic monocotyledons.
Ecologia Austral
RESUMEN. En este trabajo presentamos la primera caracterización y clasificación con imágenes de l... more RESUMEN. En este trabajo presentamos la primera caracterización y clasificación con imágenes de los ambientes y la vegetación en un área típica de la Puna seca argentina, correspondiente a la Reserva de Biósfera Laguna Blanca (Catamarca, Argentina). Se realizó un relevamiento florístico del lugar identificando 75 especies. Se describieron y se mapearon seis tipos de ambientes utilizando técnicas de Sistemas de Información Geográfica: estepas arbustivas, estepas graminosas, estepas mixtas, vegas, salinas y peladares. Dentro de las estepas arbustivas se reconocieron tres tipos, dependiendo de la especie de arbusto dominante: rica-rical (Acantholippia sp.), tolillar alto (Fabiana densa) y tolillar bajo (Fabiana spp. valle, asociándose estos patrones a los tipos de vegetación y los ambientes. Esta caracterización y mapeo permitió la comparación con otras zonas de puna y en particular, aportó información básica para el manejo de la Reserva. [Palabras clave: Puna, áreas protegidas, releva...