Application of acceleration data loggers to classify the behavior of captive Amazonian manatees (Trichechus inunguis)

Abstract

The Trichechus inunguis is endemic to the Amazon region. Observation is nearly impossible because of the turbid water, which consequently hinders study of their behaviour. In this study, we deployed the acceleration data loggers to 9 captive Amazonian manatees to classify their behaviour at INPA, Brazil. The experiments were also recorded by video camera. We classified four types of behaviours: inactive on the bottom, walking on the bottom, surfacing and swimming. Inactive and walking on the bottom were classified using standard deviation (SD) of dive depth and longitudinal acceleration. The SD of dive depth shows the low variability in inactive and walking on the bottom (ranged from 0.0 to 0.1 m), the SD of longitudinal acceleration shows the low variability in inactive (from 0.00 to 0.01 ms(-2)), high variability in walking on the bottom (from 0.01 to 0.15 ms(-2)). Mean classification accuracy was 87.1% and 84.9% during inactive and walking on the bottom, respectively. 6 manatees were fed floating vegetables during experiment, and they showed a characteristic of long surfacing during feeding time. This characteristic was probably a fair reflection of their natural behavior, as wild Amazonian manatees prefer floating and emergent aquatic plants