Behavioural laterality in foraging bottlenose dolphins (Tursiops truncatus)

Lateralized behaviour is found in humans and wide variety of other species. At a population level, lateralization of behaviour suggests hemispheric specialization may underlie this behaviour. As in other cetaceans, dolphins exhibit a strong right-side bias in foraging behaviour. Common bottlenose dolphins in The Bahamas utilise a foraging technique termed ‘crater feeding,’ in which they swim slowly along the ocean floor, scanning the substrate using echolocation, and then bury their rostrums into the sand to obtain prey. The bottlenose dolphins off Bimini, The Bahamas, frequently execute a sharp turn before burying their rostrums in the sand. Based on data collected from 2012 – 2018, we report a significant right-side (left turn) bias in these dolphins. Out of 709 turns recorded from at least 27 different individuals, 99.44% (n = 705) were to the left (right side and right eye down) [z=3.275, p=0.001]. Only one individual turned right (left side and left eye down, 4/4 turns). We hypothesize that this right-side bias may be due in part to the possible laterization of echolocation production mechanisms, the dolphins’ use of the right set of phonic lips to produce echolocation clicks, and a right eye (left hemisphere) advantage in visual discrimination and visuospatial processing.

偏侧行为（lateralized behaviour）广泛存在于人类以及众多其他物种之中。在种群层面上，行为偏侧现象提示大脑半球特化可能是这类行为的生理基础。与其他鲸类（cetaceans）一致，海豚在觅食行为中表现出显著的右侧偏好。巴哈马海域的普通宽吻海豚采用一种被称为‘坑穴觅食’的觅食技巧：它们沿着海床缓慢游动，利用回声定位（echolocation）扫描海底基质，随后将吻突（rostrums）埋入沙中以获取猎物。巴哈马比米尼群岛附近的宽吻海豚在将吻突埋入沙中前，常会完成一次急转。基于2012年至2018年收集的数据，我们发现这些海豚存在显著的右侧（左转）偏好。在至少来自27头不同个体的709次急转记录中，99.44%（n=705）为左转（即右侧身体朝下、右眼向下）[z=3.275, p=0.001]。仅有1头个体完成了右转（左侧身体朝下、左眼向下），其4次急转均为右转。我们推测，这种右侧偏好可能部分源于回声定位产生机制的偏侧化：海豚使用右侧声唇生成回声定位咔哒声，且右眼（左大脑半球）在视觉辨别与视觉空间处理中具备优势。