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The
"extra" graph in The GBS Report (page 106 in the 18 year edition and page 90 in
the 21 year editions) shows clearly part of the problem. Whilst the abundance of
the Pied Currawong appears to have decreased dramatically in Canberra in
winter, the summer abundance has increased dramatically in Canberra. It is
during the summer months when most of the nest predation occurs, as
this mostly happens when the PC have young. Actually as far as winter numbers
go, the reduction could be a bit of an illusion, as the species now has
permanent territories in Canberra and so the population is more evenly spread
all year, which reduces the former big flocks.
It is
very likely that the Pied Currawong is the major predator of birds in Canberra.
Very likely followed by the Raven and then all the raptors combined would
probably be less (although most raptors take adult birds, rather than chicks).
It would be hard to measure where cats fit in that scale. So what can be done
about the PC? Dr Harry Recher did a TV documentary about this several years ago
(based in Sydney). The ABC replays this fairly regularly. Main thing is not to
feed them, and to remove the fruiting bushes (esp Pyracantha & Cotoneaster)
that sustain them in winter. Should we engage in more active control? That is
hard to answer.
I would also point out that the Crested Pigeons arrived in Canberra in the mid 1980s
and numbers only started to increase (above the "rare" category) at the start of
the 1990s. They have done very well during the time when the PC increased its
summer prevalence, in spite of the obvious predation of nests by PC (and
others). Blackbird, Starlings, Mynas & Red Wattlebirds are also still doing
well. I'm not so sure about the smaller ones.
Philip
Why cannot something
be done about the currawongs? They are a cruel and voracious pest responsible
for the loss of many of the birds which have visited our garden. I see them
daily chasing crested pigeons, wattle birds, willy wag tails, peewits and
magpies, and I have seen one hit the head of a male Gang gang causing its
feather so fly. They have killed young crested pigeons and peewits which
have nested in our trees, and one of the young male Gang gangs which was here
until recently, but hasn't been seen, along with his brother, for about a week,
had a savage wound on its cheek and neck, which I attribute to the currawongs.
There are more of these horrible birds around our area than of anything else.
They are killing the young birds and I think there will soon be, if in fact
there are not already, more of them than of almost any other bird. To my mind
they are a far greater threat to our wildlife than cats or Indian Mynahs. I know
they are native birds, but I want to see other native birds as well. I really
think they need somehow to be controlled.
I wonder what other
chatliners think?
Charmian
Lawson
Holder
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