Wetenschappers geven aan dat bij de Campbelli de vader een belangrijkere rol speelt dan bij de Rus.
Parental behaviour was directly observed during two 30-min bouts on each of the first 18 days after birth for both Djungarian, P. campbelli, and Siberian, P. sungorus, dwarf hamster litters. Results were consistent with predictions based on earlier studies that demonstrated a positive impact of paternal presence on pup survival in P. campbelli, but not P. sungorus. The presence of the father or an aunt significantly decreased, by about half, the proportion of time that pups were alone in P. campbelli. Because brief parental absences were unlikely to result in pup cooling, analyses also considered only those absences that were 3 min or longer. By those criteria, P. campbelli pups housed with a second adult were rarely alone. In contrast, the father had little impact on the parental care received by pups in P. sungorus. Phodopus sungorus males were rarely alone in the nest with the pups, whereas both fathers and aunts in P. campbelli were alone with the pups significantly more often than the mother from mid-lactation until weaning. This behaviour reflected temporal coordination between the behaviour of the adults. Pups were left alone less often than expected based on the independent behaviour of each adult. Because there was no reason to expect alloparental care by aunts in the wild, the presence of a second adult, rather than specific parental behaviour by that adult, may be the essential component of increased pup survival. Limited observations of male parental care in the wild demonstrated that significant paternal care could occur in P. campbelli. Both field and laboratory data, however, suggest that biparental care would be facultative and adaptive under certain environmental conditions (e.g. extreme temperatures) but not all.
The males will pull the pup from the birth canal (Wynne-Edwards)
Male Djungarian hamsters not only make excellent fathers, they are also exceptional midwives.
The little creatures will help pull their offspring from the female's birth canal, lick off the birth membranes, open the baby's airways, and then eat the amniotic fluid and placenta with the mother.
There are not many mammal males that will do this. Indeed, the offspring of many species are just as likely to be eaten by their fathers as receive a comforting paw.
But Dr Katherine Wynne-Edwards and her colleagues at Queen's University in Kingston, Ontario, Canada, have shown Djungarians (Phodopus campbelli) to be totally caring in their behaviour.
The researchers were interested in what was happening to hormone levels in the animals and how this might be influencing the "behaviour of fatherhood".
"Djungarian fathers have hormonal fluctuations similar to the mother's around the time of birth," Dr Wynne-Edwards told New Scientist magazine. Oestrogen and cortisol levels rise before the birth, then fall away afterwards as testosterone rises.
This does not happen in the closely related Siberian hamster (P. sungorus), which was also studied under the dim light of the lab so as not to disturb the animals during birthing.
Although fathers in both species care for their young, Siberian hamsters only appear on the scene well after the birth. Djungarians, on the other hand, which live in a harsher desert environment, remain in the burrow at the time of birth, and help keep mother and young warm enough to survive.
"We hypothesised that because of the early hormonal changes, Djungarians would show the full range of paternal behaviour," said Dr Wynne-Edwards. They did.
In their description of the birthing, the Queen's researchers wrote in the journal Hormones and Behavior: "Males licked amniotic fluid as the pup was born, mechanically assisted the delivery, licked pup nostrils so that the pup flushed from dark purple (unoxygenated) to a bright pink (oxygenated), cleared pup membranes, consumed placenta, carried neonates, rebuilt the nest area, and remained with pups as the female laboured to deliver subsequent pups."
The males even baby sat when the females left the nest to feed.
The lab of Dr Wynne-Edwards has pioneered methods for taking blood samples for hormone testing that do not overly stress the animals.