Running the distance: embodied distance measurement is robust to social interference in fiddler crabs

Path integration (PI) is an essential navigation strategy. Through PI, animals integrate their movements during foraging into a ‘‘home vector” that allows direct return to the origin. In humans, feedback from body movement contributes to readout of the home vector: physical estimation by walking toward the origin improves people’s ability to identify the origin point. However, how such feedback affects home vector readout in other animals remains unclear. Here, we show that leg movement feedback contributes to a robust readout of the home vector despite social interference in fiddler crabs. We found that whereas the internal estimation of burrow location during the return path is subject to induced errors by social behavior, the physical estimation is not, and feedback from leg movement contributes to robust distance measurement. Our findings suggest that animals may have evolved complex navigational systems to handle the inevitable interplay between navigational cues and social behavior.