Behaviour 2019
Modeling feeding behavior of Guiana dolphins, Sotalia guianensis, in a Brazilian estuarine area
Guilherme Maricato1,2, Rodrigo H. Tardin2, Israel S. Maciel2, Deyverson Silva2, Bruna Moresco2, Maria Alice S. Alves3. 1UERJ Graduate Program in Ecology and Evolution, Rio de Janeiro, Rio de Janeiro, Brazil; 2Cetacean Bioacoustics and Ecology Laboratory, Rio de Janeiro, Rio de Janeiro, Brazil; 3Rio de Janeiro State University, Rio de Janeiro, Rio de Janeiro, Brazil

Dolphins developed feeding tactics to overcome schooling fish anti-predatory behavior and the distribution of prey species may influence dolphins tactics. We analyzed the habitat suitability of feeding tactics performed by Guiana dolphin (Sotalia guianensis) at Ilha Grande Bay (IGB), in SW Brazil. Due to IGB various microhabitats, we expected the Guiana dolphin to perform different feeding tactics according to environmental characteristics and human activities in the area. We run an ensemble model from six algorithms (600 models) to predict the occurrence of tactics: kettle, line abreast (LA), perpendicular feeding, and wall formation (WF). As explanatory variables, we used depth, seabed slope, sea surface temperature, chlorophyll, and distance from islands, rivers, and seafood farming. All tactics shared a common hotspot, but LA was predicted to occur more spread and WF more concentrated in patches along the study area. Depth was important to explain all tactics, and seabed slope also for LA and WF. The greater occurrence of tactics in shallow waters with lower slope suggests that Guiana dolphins can be a barrier to herd and capture their prey, displaying behavioral plasticity.