Vol. 1, Nº 1

This paper presents a methodology for ranking species according to conservation priorities, based on explicit, quantifiable criteria. Species are ranked through an index which is a sum of values assigned to 12 factors relevant to their survival: continental distribution, national distribution, extent of the use of habitat, extent of the use of vertical space, body size, reproductive potential, trophic amplitude, abundance, taxonomic singularity, singularity, extractive action and degree of protection of the species. The method was applied to 141 autochthonous tetrapod species of the Argentine Nothofagus forests. Results were compared to other qualifications by international and national organizations. The method is objective, and therefore repeatable and verifiable. It can be updated as new information becomes available. It is a useful guide for conservation and management, and because of its simplicity can expeditiously respond to concrete requirements. If the circumstances under which the method was calculated persist, it may become predictive.

The aim of this study was to investigate the diet of Calomys musculinus in crop fields and their borders, and its relationship to availability in these habitat types. Vegetation censuses were carried out, and microhistological analysis of the stomach contents of captured animals. C. musculinus presented a granivore diet, with oligophagous behaviour, basing its consumption mainly on two seed species: Chenopodium sp. and Amaranthus sp. A marked correlation between plant availability and the items consumed by C. musculinus was not shown, although it was found that the weeds of the habitat were important food sources.

El objetivo de nuestro trabajo fue estudiar la dieta de Calomys musculinus en el ambiente de cultivo y sus bordes en relación a la disponibilidad vegetal de estos ambientes. Para ello se realizaron censos vegetales y se utilizó el análisis microhistológico de los contenidos estomacales. C. musculinus presentó una dieta granívora, con un comportamiento oligófago, basando su consumo principalmente en dos especies de semillas: Chenopodium sp. y Amaranthus sp. No se encontró una marcada correlación entre la disponibilidad vegetal y los items consumidos, siendo las malezas del hábitat importantes como fuente de alimento.

The problem of loph homologies among the upper cheek teeth of the caviomorph rodents and the polarity of some of the observed changes are reanalyzed. This analysis is made upon the evidences provided by both living and fossil representatives. It is concluded that pentalophodonty is an homology for the caviomorphs. There is only one pentalophodont pattern, while there are two different tetralophodont configurations. In all of them, the third loph is a mesoloph. The tetralophodont patterns represent successive steps of a general process of loph reduction. In brachyodont molars, this reduction is part of the adaptation to open environments, such as the development of hypsodonty is. The scarcity of pentalophodont genera in the fossil record and their present restriction to the Brazilian subregion are related to the early development of open environments in the southern part of South America.

Se discute el efecto de eventos climáticos, tal como los temporales de nieve, sobre poblaciones de camélidos silvestres. Las tormentas de nieve del año 1984 causaron la mortandad, directa e indirecta, de 181 camélidos: 148 vicuñas (Vicugna vicugna) y 33 guanacos (Lama guanicoe) en un área bajo estudio de la Reserva de la Biósfera de San Guillermo, Provincia de San Juan, Argentina. Analizando la mortandad en vicuñas, no se encontró diferencias significativas por sexo, pero si mayor mortalidad (P < 0.001) en los juveniles (< 1 año de edad). El hábitat de quebradas mostró una marcada vulnerabilidad (P < 0.001) en comparación con llanos y vegas para ambas especies. Los números de camélidos muertos representaron el doble de lo encontrado en la misma área en seis años anteriores, aunque en términos poblacionales constituyen el 4.5% (vicuña) y el 1% (guanaco) de la población censada previamente.

This study deals with the effects of snowstorms on the population structure of wild camelids. The severe winter storms of 1984 influenced the mortality (direct and indirect) of 184 camelids: 148 vicuñas (Vicugna vicugna) and 33 guanacos (Lama guanicoe) in the San Guillermo Biosphere Reserve, San Juan Province, Argentina. Considering vicuña mortality, no significant differences were found in mortality by sex; juveniles (< 1 year old) were significantly affected (P < 0.001). Considering both species, more dead animals were found in gullies (P < 0.001) than in other habitats (plains and marshes). The number of deaths in 1984 was twice that found in the same area during the previous six years, representing 4.5% and 1% of the censused vicuña and guanaco populations respectively.

Revisión del libro Neotropical wildlife use and conservation. J.G. Robinson y K.H. Redford, editores. 1991. The University of Chicago Press, Chicago. 520 pp.