Spatial orientation in echolocating harbour porpoises (Phocoena phocoena)

Area of Science:

• Marine Biology
• Bioacoustics
• Animal Behaviour

Background:

• Echolocation in toothed whales (odontocetes) is primarily studied for target detection and discrimination.
• Previous research has focused on stationary or approaching targets, neglecting navigational aspects.

Purpose of the Study:

• To investigate the use of echolocation for spatial orientation and navigation in harbour porpoises.
• To analyze the relationship between echolocation behavior and swimming patterns during navigation tasks.

Main Methods:

• Synchronized high-frequency audio recordings and video analysis of two trained harbour porpoises.
• Measurements of echolocation click intervals and lag times during a navigation task in an outdoor pool.

Main Results:

• Harbour porpoises exhibited range-locking behavior, decreasing click intervals as they approached specific positions, indicating landmark use.
• Click interval changes correlated with the two-way-transit time of echoes from focal objects.
• Lag time between echo reception and the next click varied with task difficulty, suggesting adaptive echolocation strategies.

Conclusions:

• Echolocation in odontocetes serves a role in spatial orientation and navigation, beyond target detection and classification.
• Focal objects can function as navigational landmarks for harbour porpoises, utilized through echolocation.
• Echolocation behavior is adaptable and task-specific, supporting complex navigational functions in cetaceans.