91av

MOST mammals are lousy fathers. Those that don’t eat their young do little to
help in the birth apart from making encouraging noises. Djungarian hamsters
(Phodopus campbelli), though, are paws-on dads.

In the first published case of its kind, Canadian scientists have watched
Djungarian fathers help pull their babies from the birth canal, lick off the
birth membranes, open the baby’s airways, then share a snack of afterbirth with
the mother.

There have been observations of this in other species
(91av, 12 December 1998, p 38).
But Katherine Wynne-Edwards and her colleagues at
Queen’s University in Kingston, Ontario, are the first to look at why it
happens. “Djungarian fathers have hormonal fluctuations similar to the mother’s
around the time of birth,” she says. Oestrogen and cortisol levels rise before
the birth, then fall away afterwards as testosterone rises. This doesn’t happen
in the closely related Siberian hamster.

Moreover, although fathers in both species care for their young, Siberian
hamsters only appear on the scene well after the birth. Djungarians are also
from Siberia, but live in a harsher desert environment, says Wynne-Edwards.
Djungarian fathers 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,” says Wynne-Edwards. They did.
Not only were they exemplary midwives, she says, “we saw the mother and father
both holding the afterbirth with four little paws, sharing it fifty-fifty”.

“There are probably lots of species that do this,” she adds. But few
researchers have tried to find out as it is hard to measure hormones without
stressing animals.