Comparative spatial cognition in wild Tanganyikan cichlids: navigation performance varies with home range and shelter availability

Spatial cognition varies widely even among closely related species, and identifying the ecological drivers of this variation remains challenging because species typically differ in multiple aspects of their ecology simultaneously. Here we performed wild experiments to compare spatial navigation in seven related species of shell-dwelling cichlids from Lake Tanganyika that share fundamental aspects of their ecology but vary in home range size and shelter availability. We displaced territorial males at successively greater distances (30 cm to 15 m) from shelters, using video tracking and automated 3D terrain reconstruction to measure return paths and homing success. We complemented this with onshore experiments examining landmark use and memory for shell locations. Of the seven species tested, three (Lamprologus ornatipinnis, L. ocellatus, Neolamprologus meeli) reliably returned to their home shells while four species (N. multifasciatus, N. brevis, N. pulcher, Telmatochromis temporalis) sought shelter in the nearest refuge. Among the navigating species, homing success declined with displacement distance, and long-distance performance (at 15 m) differed: N. meeli (largest range, fewest shelters) succeeded in 80% of trials, while L. ocellatus and L. ornatipinnis (smaller ranges, marginally more shelters) succeeded in only ~ 10% of trials. Arena experiments revealed that the two better-performing species in the field preferentially searched in areas previously associated with their home shell, with N. meeli showing additional use of experimental landmarks. Our findings provide a detailed comparative foundation for future work, highlighting how ecological context shapes spatial cognition in natural populations.