Vieses amostrais para aves no Pantanal : influência das rotas de acesso, sazonalidade e grupos taxonômicos sobre registros de coleções biológicas

Abstract

Sampling bias of biological data is a common problem that can directly affect how biological patterns are depicted, resulting in knowledge shortfalls. Studies show that biodiversity data are frequently under taxonomic, temporal and spatial bias. The Pantanal is one of the largest extensions of wetlands on the planet and has the highest bird species richness for this type of ecosystem. Its complexity and heterogeneity, caused by a marked inundation pattern, contribute to local diversity. Knowledge shortfalls and sampling bias were already reported in Brazil for some taxonomic groups. Although Aves is considered a well-known group it is still subjected to bias, therefore identify and map these shortfalls for this group may provide an overview on general trends of how these biases work, as well as their causes. Therefore, this project aimed to investigate potential knowledge shortfalls and spatial, temporal and taxonomic bias for Pantanal birds, based on records of biological collections available on different online biodiversity databases. The data were filtered for geographic coordinate accuracy and were updated taxonomically. The highest concentrations of records were located in the northern Pantanal, and the results also indicate that the sampling intensity is strongly biased towards the proximity of access routes. With almost 95% of unsampled area, the spatial coverage of bird’s records, was found insufficient in Pantanal. We identified seasonal bias regarding the inundation dynamics of Pantanal with a large amount of sampling effort concentrated during the dry season. About 41% of the species with known occurrence in Pantanal had no records on the database. We found a clear difference in sampling effort towards Passerine, with non Passerine families being three times more undersampled than Passerines. This trend may be reflecting the limitations from the use of mist nets, currently the most common method applied for bird collection in Brazil. Strategies aiming to reduce these spatial, seasonal and taxonomic biases are needed and can be highly positive to increase the ornithological knowledge of Pantanal.