Can I
guess from Geoff's story that the birds at the cricket were
swallows?
The
comment by Chris provides a consistent context for me to describe what happened
with the next box (from the Myna project) I can see from my kitchen and study
window in this current spring & summer. Apart from a week away in
January I am pretty much home all day every day, so I think this is a full
story. Last year (2010-2011) it attracted only Mynas. This year it had a pair of
Eastern Rosellas attending it from GBS weeks 36 to 43. The male would sit on the
box and chatter and tail wag whilst the female would go in. In week 43 I
observed one dispute lasting just a minute or two of this pair of Eastern
Rosellas with a pair of Crimson Rosellas at the site and have never seen the
Eastern Rosellas return. The pair of Crimson Rosellas were an adult
plumaged male with a female that is still in mostly green plumage.
They attended from weeks 43 to 48. I assumed just one pair and whilst the
female spent a lot of time in the box, I could usually see her head at the
entrance hole which shows she could not have been sitting in the box, just
clinging to the inside wall. At one time I saw a second pair of Crimson Rosellas
also one adult plumaged one and one still in mostly green plumage have
a fight over the box. Such that then I didn't know who was the "rightful owner"
as I couldn't see any difference between these two pairs. In week 48 we had a
heavy rainstorm and they abandoned it and nothing has used it
since.
Although further to Chris' idea I don't know about the
generality in birds but it is of course very common in mammals that males take
longer to achieve breeding status and appearance than females. May be relevant
but probably not, as the mating systems leading to that are commonly very
different between mammals and birds, except I suppose the very polygamous groups
of birds.
Philip
Thanks for this Geoffrey.
I cannot help but wonder if it is a general feature that where males and
females wear similar adult plumage, females take longer to acquire it than do
males. Appears to be the case with Magpies and I wonder about Crimson
Rosellas where so often an adult plumaged male is paired with a female that has
not yet acquired the full adult plumage. Anyone with aviary experience
care to comment?
Chris
From: Geoffrey Dabb [ Sent: Friday,
27 January 2012 11:20 AM To:
Subject: [canberrabirds] Field
guides strike again
Well, that was Australia Day. To the long-time observer
it is getting excruciatingly more Australian each year, in fact you’d wonder
just how Australian it can get. To the bird observer, the afternoon
was enlivened by the commentary at the Australian open tennis about the
‘starlings’ swooping so low over the court that they were in danger from the
swishing racquets. Chasing moths, we were told. Oh well, no
worse on bird ID than the golf commentators.
With friends from Merimbula in town for the bridge
competition we were able to have the White-headed Pigeon discussion again.
This begins with the assertion that the females can be told by their mottled
greyish breasts. This rumour can be traced to the field guides which,
again, are guilty of excusable oversimplification. The HANZAB illustration
supports the theory. However according to the HANZAB text females are just
slower to move from the juvenile plumage, older females being indistinguishable
from adult males. Accordingly, in the below, the left bird is probably a young
female, the middle bird is only probably a male but could be an old female, and
the right hand bird is a non-old female.
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