I live a Wangaratta (at time between Uni.) and have noticed an increase in
the number of White-backed Magpies over the last five years. The group
that occurs around my house and paddock contains at least one seemingly
pure white-backed male and a number of black-backed/white-backed
hybrids. Surrounding groups on neighbours farms also seem to contain
white-backed birds or hybrids as well. The black-backed race though is
still predominant, white-backed birds stand out as they are different.
Lawrie Conole's thoughts on that the Great Divide in the past kept these
two races apart is an interesting one. Clearing of forest would seem to
create Magpie habitat, each repsective race would move together and
interchanging of genes would be able to occur, Wangaratta is about 100km
from the main divide, but quite close to forests of the on the northern
side of the divide which could be the source of these birds. Also of
note is that around La Trobe University I have noticed a
white-backed/black-blacked hybrid tending more toward black-backed
plumage. It seems the interchange of birds occurs both ways over the
divide. Next time you are travelling along the Hume Freeway from Melbourne
to northern Victoria observe the Magpies and see if you can notice any
changes in their plumage from north to south. Also another question, does
any hybridisation occur between Black-backed Magpies and the Western,
dorsalis race in south-western Australia ?
Michael Ramsey,
Bundoora, Vic
|
