Social isolation does not alter exploratory behaviour, spatial learning and memory in captive Damaraland mole-rats (Fukomys damarensis)

Abstract

Exploratory behaviour, spatial learning and memory affect the survival of animals and appear to be dependent on the specific habitat that a species occupies. Good spatial navigation and memory are particularly important for subterranean animals, as it is energetically expensive to inhabit this niche. Damaraland mole-rats are subterranean mammals that live in colonies with organised social structures. Damaraland mole-rats have been maintained in the laboratory for many years and can be housed in groups or individually. We evaluated the effect of social isolation on the exploratory behaviour and spatial memory of single-housed and colony-housed animals and also considered potential differences in animals with different social statuses. We predicted that solitary housing would increase anxiety-like behaviour and result in higher activity and more errors when solving a maze. Exploration by colony- and single-housed mole-rats was tested in an open-field test, where all individuals explored readily. Single-housed queens and non-breeding females showed increased activity and spent more time in tunnels, which can be explained by increased anxiety. In the Y-maze, improvements in solving the maze were observed in all experimental groups, except in single-housed non-breeding females. In addition, all males showed a decrease in the number of errors in the maze. Spatial learning is thus apparent but could not be conclusively proven. It was possibly underestimated, as magnetic cues that may be used by mole-rats as stimuli for navigation were removed in the experimental setup. Overall, it appears that social isolation has a limited effect on the exploratory behaviour and spatial learning of Damaraland mole-rats.

Good exploration and navigational skills are important for subterranean mammals because they inhabit an energetically costly environment. Damaraland mole-rats are social animals, but in captivity, they can be housed in colonies or individually. Social isolation may have effects on their exploratory behaviour and memory performance. Overall, colony-housed and individually housed mole-rats explored readily, but single queens and non-breeding females were more active, possibly related to increased anxiety-like behaviour when housed individually. All groups, except single-housed non-breeding females, also showed improvements in solving a Y-maze, while both colony and single males made fewer errors in the maze over time. Thus, learning is probable but may have been underestimated in this experiment. In general, social isolation has a limited effect on Damaraland mole-rat exploration and spatial learning.