Abstract: We present herein the first records of evidence of bottom contact behavior by Sotalia guianensis. From April 2002 to December 2004, boat cruises were conducted along a 135-km stretch of coast on the Abrolhos Bank, eastern coast of Brazil. Evidence of bottom contact behavior was observed directly or through photographs on 25 occasions during the study period. On 16 occasions, one or more dolphins were observed with mud adhered to their dorsum, flanks, peduncle, head/melon, or dorsal fin. On five occasions, a mud-plume suspended by the movement of the dolphins and their contact with the bottom was observed. During four other occasions, both types of evidence (mud adhered to the body and mud-plume) were observed for the same group of dolphins. Contact by cetaceans with the sea floor is widely reported for several species and seems mainly related to feeding behavior, which probably is also the case for the observation presented here.

Key Words: estuarine dolphin, Sotalia guianensis, bottom contact, feeding behavior, mud-plume, Abrolhos Bank, Brazil

Document Type: Research article

DOI: 10.1578/AM.32.2.2006.140

Page Numbers: 140-144