Padrão de atividade e fatores que afetam a amostragem de mamíferos de médio e grande porte na Amazônia Central

Abstract

Surveying and monitoring of elusive animals with naturally low densities and large home ranges, such as many medium- and large-sized mammals, is challenging. The distribution and ecology of many species of medium- and largesized Amazonian mammals remain poorly understood. Scarcity of reliable data on species’ occurrence and ecology can lead to weak and inappropriate conservation actions. Additionally, low capture rates can preclude detailed analyses. We carried out two camera-trap surveys in the dry season of two consecutive years with an overall sampling effort of 4894 camera trap*days in Amanã Sustainable Development Reserve, Central Amazonia. The sampling grid consisted of up to 64 baited or unbaited camera trap stations. During the study, we recorded 22 species of mediumand large-sized terrestrial mammals, of which 11 are categorized as threatened or data deficient, either globally or in Brazil. The activity patters of most of the 15 medium- and large-sized terrestrial mammals species analyzed are largely concordant with existing natural history accounts. We found weak relationships among daily activity patterns of predators and their potential prey, and there was no evidence of temporal segregation among large carnivores. One of the recorded species was the bush dog (Speothos venaticus). Although its distribution covers the entire Amazon basin, the presence of S. venaticus remains hypothetical over vast areas of the Amazon. The records of bush dog presented in this study reduces a large gap in the known distribution of the species in Central Amazonia, and include the first documentation of the species from forest seasonally flooded by black water (Igapó). We tested the efficiency of the use of trails and bait in improving capture rates of medium- and large-sized terrestrial mammals in camera-trap surveys in the Amazon. We also tested if the quality of photographic records of naturally marked felids is enhanced by the use of bait. Contrary to reports in the literature, we found that neither bait nor trails increased the number of photographic records of carnivores, and that they reduced the number of records of non-carnivore species. However, the quality of photographs for individual identification of naturally marked felids was greater at baited camera-trap sites. We conclude that the use of bait and trails should be carefully considered at the planning stage of any camera-trap studies as they may influence detection rates of species of interest.