Distance Estimation in Reproduction Tasks in a Harbor Seal (Phoca vitulina)

Abstract

Harbor seals commute between haul-out places and feeding grounds close to the shore or in the open ocean, which is considered a low structured environment, at first sight not providing many cues for orientation/navigation. Nevertheless, seals are well-oriented. For returning to a specific location, seals may use both external and internal cues to, for example, perform path integration requiring the integration of distances traveled and angles steered. We herein assessed the seal’s ability to estimate distances, previously swum or unknown, in reproduction tasks. Reproduction tasks refer to an experimental paradigm in which the experimental animal is required to swim a specific distance first and subsequently reproduce this distance, with visual cues present or absent. The seal was able to estimate and then reproduce distances (0.5–18.5 m) with the smallest error below 10% of the actual distance, and its precision was higher with distances repeatedly swum compared to its performance with unfamiliar distances. In the absence of visual cues, the seal’s performance slightly dropped; however, it was still able to perform the task with an error of 21%. In conclusion, distance estimation may help seals to navigate precisely towards their goals, even if, for example, visual information is not available.