Title: Notes on the distribution of tucuxi, <i>Sotalia fluviatilis</i> (Cetacea: Delphinidae), in Ecuadorian Amazonia
Abstract: Sotalia fluviatilis, commonly known as tucuxi, is widely distributed in the main tributaries of the Amazon Basin in northern Brazil, Peru, Ecuador, and Colombia (Borobia et al., 1991; Jefferson et al., 1993; da Silva and Best, 1996; Nowak, 1999). In Ecuador, tucuxi is an elusive species with apparently low population densities (Denkinger, 2001) and evidence of its geographical distribution is patchy (Utreras et al., 2001). Little is known about its habitat requirements, movement patterns or population dynamics (Utreras, 1996; Utreras et al., 2001). This paper reports occasional sightings of tucuxis made by different observers, including the authors, during the last 15 years in the Ecuadorian Amazon, in an attempt to add new information on the occurrence of the species in Ecuadorian waters. In Ecuador, S. fluviatilis has been recorded to date as far north as the Putumayo River along the Colombian border. The southernmost records include the Morona and Mangosiza Rivers, near the southeastern Peruvian border. The majority of records come from the Putumayo, Aguarico, Napo and Yasuni Rivers (Table 1). This, however, can reflect higher observation effort in those areas. S. fluviatilis records for