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Thursday, 20 April, 2000, 10:33 GMT 11:33 UK
Hamster is excellent midwife
Hamster Wynne-Edwards
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.

Hormonal fluctuations

The researchers were interested in what was happening to hormone levels in the animals and how this might be influencing the "behaviour of fatherhood".

Hamster Wynne-Edwards
The researchers are interested in the hormones that will influence a father's behaviour (Wynne-Edwards)
"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.

Pup nostrils

"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.

All images are the copyright of Dr Wynne-Edwards

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