Behavioural laterality in foraging bottlenose dolphins (Tursiops truncatus)

Area of Science:

• Ethology
• Marine Biology
• Neuroscience

Background:

• Lateralized behavior, indicating hemispheric specialization, is observed across species, including cetaceans.
• Dolphins, specifically common bottlenose dolphins (Tursiops truncatus), display a pronounced right-side bias in foraging activities.
• A specific foraging technique, 'crater feeding,' involves dolphins burying their rostrums into the seabed to capture prey.

Purpose of the Study:

• To investigate and quantify the lateralization of turning behavior in bottlenose dolphins during crater feeding.
• To determine if a population-level bias exists in the direction of turns executed during this foraging strategy.
• To explore potential neurological underpinnings, such as echolocation and visual processing lateralization, for the observed behavior.

Main Methods:

• Behavioral data collection from common bottlenose dolphins off Bimini, The Bahamas, between 2012 and 2018.
• Recording and analysis of 709 turning events during crater feeding from at least 27 individual dolphins.
• Statistical analysis to determine the significance and directionality of the observed turning bias.

Main Results:

• A significant right-side bias was identified, with 99.44% (n=705) of recorded turns being to the left (indicating a right-side dive).
• Only one individual exhibited a right turn (left-side dive) in the recorded instances.
• The observed bias was statistically significant (z = 3.275, p = 0.001).

Conclusions:

• Bottlenose dolphins off Bimini demonstrate a strong population-level bias towards left turns (right-side foraging) during crater feeding.
• This lateralization may be influenced by the specialized use of echolocation and potential hemispheric advantages in visual processing.
• Further research into the lateralization of echolocation production and visual-spatial abilities is warranted to explain this behavioral asymmetry.