Figure 1: Experimental chamber for radial search paradigm.

(a) A plexiglass, 28-cm square chamber divided into two sections, was used for the first set of experiments. A holding chamber (top) was separated from the testing chamber containing the food and accessed through a small hole that was blocked by a vertical bar until each trial started (not shown). The box was accessed between trials by removing the lid, which sat on walls coated with vacuum grease to form an airtight seal. Eastern moles are small mammals typically weighing between 50 and 90 g. (b) An air-pressure monitor recorded respiration, and sniffing correlated with the time stamps of frames captured from high-speed video allowing nose movements (lines) to be correlated with sniffs (circles). Supplementary Movie 1 shows sniffs correlated with nose movements. (c–e) Example of mole search behaviour and nose movements correlated with sniffing. Trials were initiated approximately 1 min after food placement and trials usually lasted 5–10 s. Scale bars, 8 cm in a, 1 s in b and 4 cm in c.