Insectivorous bats navigate mainly by echolocation but may incorporate multisensory cues. Parsing the relative contributions of different senses to navigation is difficult in wild bats. In the lab, spatial memory and navigation in rodents is commonly investigated using multiple T-mazes. We trained crawling free-tailed bats (Tadarida brasiliensis) to navigate a 60 × 60 cm multiple (10 turn) T-maze within an artificial magnetic field and then manipulated the sensory environment to quantify the relative importance of vision, hearing, and magnetic field cues for navigation performance. We tested whether (1) reversing the magnetic field polarity, (2) altering or removing light from the arena, or (3) presenting an acoustic jamming stimulus would increase maze travel times and number of errors made. Results showed that reversing the magnetic field had no significant effect on maze travel times in either ambient light or darkness. However, in total darkness, mean travel times increased by 75% relative to both broad spectrum white light and 650–750 nm red light. Presentation of an acoustic jamming stimulus mimicking the pulses of other bats significantly increased travel times by 50%. The results suggest that bats navigating a confined space supplemented their biosonar with visual cues but not magnetoreception.
Lemus et al. (Wed,) studied this question.