|
Hi Birders,
In recent time, three people have
commented on the breeding habits of the Channel-billed Cuckoo (Messers Adderley,
Cox & Scouler) but no one has indicated what the whole picture is in respect
to the Channel-bills treatment of the hosts eggs & or young.
In their review of the habits of the
Channel-billed Cuckoo (Goddard & Marchant (1983 Aust. Birds
17, 65-72) they noted that the female tampered with the eggs of
the host but gave no details. Brooker & Brooker (1989 Cuckoo Hosts in
Australia) also commented on the lack of information about the breeding
biology. Even when HANZAB Vol 2 was published in 1999 there was still no
reference to the Cuckoos tampering with hosts' nests before laying although it
is known that unlike other cuckoos, the young channel-bills in the nest don't
eject their hosts chicks, rather the hosts chicks just die of starvation,
because the bigger cuckoo chicks out-compete them for the food.
So it was left to a very competent
observer, Dariel Larkins of North Turramurra who provided three detailed
eye-witnessed accounts of Channel-bills, which on their arrival at the
breeding grounds either removed mostly by flicking out, Pied Currawong chicks
from the nest, and or removing (and eating ?) the eggs (1994 Aust Birds
28, 7-10). Presumably this was done to make the Currawongs re
lay and so enable the Channel-bills to better synchonise their egg laying so
that their chicks can hatch first or at least at the same time as the currawongs
(and other hosts). Unfortunately her article was not included in the HANZAB
references.
The rarity of the observation of the
actual action of Channel-bills removing the hosts chicks is such, that this was
the reason why I was skeptical of Peter Adderly's finding of 5 currawong chicks
on the grounds and attributing their death to Channel-biled Cuckoos. It had been
pretty windy at the time, the chicks could have been blown from the nests, or
Brush-tailed Possums (as I have seen in the past) could have been guilty of
interfering with the currawong nests, or the currawongs could have been having
territorial fights as do House Sparrows and other birds. Bird watchers have to
be wary of ascribing guilt by association without actual seeing the action which
they assumed has happened. However it was worthwhile that Peter, Bruce &
Colin should have brought these matters to our attention. I would urge everyone
to go and look to see what all the fuss is about when the Channel-bills and
Currawongs are squabbling in your garden.
Incidentally, Allan Benson and I have
listened to the tapes of Peter Adderly and conclude that the bird calling on the
tapes is a Noisy Friarbird and not a Channel-bill.
Alan
Morris
| 