Paternal behaviour in biparental hamsters, Phodopus campbelli, does not require contact with the pregnant female

Abstract

Male Djungarian hamsters, Phodopus campbelli, are naturally paternal and actively participate in the birth and care of growing pups. Males undergo hormonal changes several days prior to the birth of their pups. Although these changes cannot be attributed to pup stimuli, they are nevertheless essential for the expression of complete paternal behaviour during and following the birth of the litter. We conducted two laboratory experiments to test the hypothesis that cues from the pregnant female are important for the expression of midwife and paternal behaviour in Djungarian hamsters. In experiment 1, we allowed pairs to mate, then removed the sires and housed them in separate cages in the same room as their mates. We then either reintroduced the sires 5min later, or on the evening before the birth of their litter, or we did not reintroduce the sires. In experiment 2, we replicated the treatment of housing the sire and the female in separate cages in the same room until just prior to the birth of the litter, but we added another group of sires that were housed in a different room (with independent air handling) until just prior to the birth of their litter. Male behaviour was not altered in any of the treatments: (1) reunions just a few hours before the birth were free of aggression; (2) males participated as ‘midwives’ during the birth at levels similar to previous studies; and (3) males provided extensive paternal care during pup growth, staying with pups on the nest during development and rapidly approaching, contacting and retrieving a 3-day-old pup that was experimentally displaced from the nest. We conclude that physical, olfactory, auditory and visual stimuli from the pregnant female are not necessary for the expression of paternal behaviour in this species. Alternative hypotheses, including the hypothesis that paternal behaviour does not require external stimuli, are worthy of exploration.