Hurtado-Parrado, C., Cardona-Zea, Á, Arias-Higuera, M. et al. 2019. Behavioral patterns of laboratory Mongolian gerbils by sex and housing condition: A case study with an emphasis on sleeping patterns. Journal of Veterinary Behavior 30, 69-79.

The behavioral patterns of Mongolian gerbils (Meriones unguiculatus) housed individually and in same-sex groups (siblings) were characterized. Gerbils were continuously video-recorded 24 hours (day 1) and 120 hours (day 5) after housing conditions were established (no environmental enrichment was implemented). Video samples totaling 2016 minutes were scored to obtain measures of maintenance (drinking, sleeping, grooming, and eating), locomotor (jumping and rearing), communication (foot stomping), and stereotyped behaviors (gnawing bar and digging), which were compared across housing conditions and sex. Irrespective of sex or housing, gerbils dedicated between 65 and 75% of the day to maintenance behaviors; more than 50% of this time was dedicated to sleep. Time allocated to other behavioral states—for example, bar gnawing, digging, and eating—remained below 5% of the observation time. A comparison of day 1 and day 5 only indicated an increase in water consumption. Housing only affected water-drinking time during day 1, with individual gerbils spending more time drinking than grouped animals. Independent effects of sex were only observed for sleep and the overall behavioral category of maintenance during day 5. Further exploration of sleep patterning across different periods of the day was conducted. Distribution of sleeping was less systematic during day 1 than during day 5, most likely related to habituation to the new housing conditions. During day 5, regardless of sex or housing, gerbils showed the lowest levels of sleeping at the start of the dark cycle (18:00-20:59 hours) and the highest around midnight (00:00-02:59 hours). Although these findings require future replication with more robust groups of animals, they overall support the notion that captive gerbils are crepuscular—that is, more active during light-to-dark transitions—and suggest that changes in housing produce disruptions of activity-sleeping patterns and water consumption of adult gerbils.