The echolocation ability of the beluga (Delphinapterus leucas) to detect targets in clutter

A beluga (Delphinapterus leucas) was trained to detect different length cylinders in front of a clutter screen at five separation distances. The clutter screen consisted of 300, 5.1‐cm‐diam cork spheres located behind the targets. The clutter screen was used in two positions: perpendicular to the body axis of the beluga (90° grazing angle) and rotated 22° (68° grazing angle). Five hollow stainless‐steel cylinders (3.2‐cm‐diameter and 0.38‐cm wall thickness) of different lengths (14, 10, 7, 5, and 3 cm) were used as targets. Detection data were collected on the beluga's performance as a function of the separation between targets and the clutter screen. The beluga's performance was above 80% correct detection for the 14‐ and 10‐cm cylinders as the separation distance decreased from 10.1 to 5.1 cm for both grazing angles. For all targets except the 3‐cm cylinder, the beluga's detection was higher at 0‐cm separation than at 2.5‐cm separation. The beluga's detection performance was higher at 68° than at 90° gr...