Balancing power production and environmental conservation can be problematic. The objective of this study was to investigate the abundance of marsh deer in the Paraná River Basin, above the Sergio Motta (Porto Primavera) Dam, before and after the impact of the dam closure. A fixed-wing, flat window aircraft was used to survey study transects. Observations were recorded based on the distance sampling line transect method, assuming that the detection probability decreases with increased distance. The abundance of marsh deer in the survey region prior to flooding was estimated to be 974 individuals (CV = 0.23). The overall abundance dropped from 974 to 444 (CV = 0.26) individuals after flooding, an overall reduction of 54%. This reduction can be attributed to the direct impact of the flooding process, but it was likely exacerbated by indirect effects, such as increased disease, hunting, and reduction in food availability. Prior to flooding, the marsh deer was distributed widely throughout the dam's catchment area; however, the marsh deer habitat was almost completely destroyed by the flooding process. This situation highlights the need to implement management strategies that ensure the survival of the remaining fragmented population.

O estudo de grandes áreas de pastejo, principalmente no que diz respeito ao seu uso pelos animais, é difícil, tanto na forma de amostragem, quanto na maneira de analisar os dados obtidos. Nesse contexto o Sistema de Informação Geográfica (SIG) surge como ferramenta útil, capaz de viabilizar estudos ecológicos e comportamentais associados ao uso do espaço e dos recursos nele alocados. Dentre as ferramentas principais de um SIG com importância para o estudo de ecologia de pastagens, podemos citar a determinação de áreas de uso e trilhas, além das sobreposições, regressões e multi-regressões de mapas (compondo por exemplo: áreas de pastejo e malhadouros, características do solo, concentrações espaciais de nutrientes nas forragens, etc.). Por ser uma ferramenta de modelagem espacial computadorizada nos permite compreender e analisar de maneira mais adequada, os fenômenos de distribuição geográfica muitas vezes imperceptível nas coletas de dados convencionais. A distribuição dos animais em uma área qualquer resulta de ações combinadas de forças internas ao grupo social (por exemplo, hierarquia de dominância, liderança e formação de subgrupos) e externas a ele, como por exemplo, o posicionamento de bebedouros, sombras e cercas, que podem atuar como condicionadores de pastejo. Assim, com o entendimento do complexo arranjo do ambiente de pastagem com o uso do SIG, incluindo os fatores bióticos (tipos de vegetação, por exemplo) e abióticos (relevo), é possível desenvolver estratégias de manejo de forma a modular o comportamento dos animais, reduzindo os problemas que podem causar degradação nos recursos deste ambiente. Porém, a escolha do melhor conjunto de técnicas de análise dentro do SIG e de suas possibilidades de uso ainda está por vir, principalmente no que diz respeito às suas aplicações às condições e necessidades brasileiras.

The study of great grazing areas, mainly so that concerns the use for the animals, it is difficult, so much in the sampling form, as in the way to analyze the obtained data. In that context the Geographical Information System (GIS) it appears as useful tool, capable to make possible ecological and behavior studies associated to the use of the space and of the resources in him allocated. Among the main tools of a GIS with importance for the study of ecology of pastures, we can quote the determination of use areas, trails and overlay, regressions and multi-regressions of maps (for instance: grazing areas, soil stains, resting places, space concentrations of nutrients in the forages, etc.). For being a tool of computerized spatial modeling, allows us to understand and to analyze in a more appropriate way, the phenomena of geographical distribution many times imperceptible in the collections of conventional data. The distribution of the animals in any area results from combined actions of internal forces to the social group (for instance, dominantly hierarchy, leadership and subgroups formation) and external to him, as for instance, the water bunker positioning, shadows and fences, that can act as conditioning of grazing. Like this, with the understanding of the compound arrangement of the pasture atmosphere with the use of GIS, including the biotic (vegetation types, for instance) and non- biotic factors(relief), it is possible to develop strategies of form handling to modulate the behavior of the animals, reducing the problems that can cause degradation in the resources of this adapts. However, the choice of the best group of analysis techniques inside of GIS and the possibilities of use it is still for coming, mainly in that concerns their applications to the Brazilian conditions and needs.