Evidence that seals may use echolocation

Abstract

Harbour seals (Phoca vitulina ), like many phocid species, forage to some extent at night¹. Although nocturnal mammals typically rely on non-visual sensory channels, seals have adapted to low light levels by sharpening their visual sense². Although enhanced visual sensitivity would be functional in clear water, many species inhabit turbid coastal or estuarine regions where vision is sometimes of limited use even in daylight. Here we present experimental evidence in support of the contention that when visual cues are not available, seals use echolocation. Our results help to explain why previous attempts to demonstrate sonar abilities in pinnipeds have been unsuccessful.