Figure 1.

The novel extractive foraging tasks presented to the smooth-coated otters. (1) A simple plastic box (55 × 175 × 130 mm); (2) a plastic box with clips on the lid (45 × 135 × 135 mm); this box was used as both tasks 2 and 3, once with four clips closed (task 2) and then with two clips closed and two clips removed (task 3); (4) a round plastic jar with screw-top lid (180 × 90 mm diameter); (5) a round plastic tub with a pull-off lid (70 × 170 mm diameter); and (6) a square plastic jar with screw-top lid (180 × 85 × 85 mm). Each task was baited with half a fish and covered with its respective lid. The tasks are numbered in assumed order of difficulty with 1 being the easiest and 6 being the hardest.