Aha, Martin, a question of one’s perspectives
perhaps. I would have thought it was tempting to attribute extensions due
to escapes and introductions to natural causes.
Joe Forshaw, a silent reader of this chatline, says he agrees
broadly with my position on the Long-billed, the true correlation being with
human settlement, and we should look at Australian Parrots Third Edition
From: martin butterfield
[
Sent: Saturday, 19 December 2009 10:42 AM
To: Geoffrey Dabb
Cc: Cog line
Subject: Re: [canberrabirds] spectacular gathering of corellas (not
local!) - and channel-billed cuckoo in Wanniassa yesterday
Geoffrey
It is always tempting to attribute range extensions to escapes and
introductions.
Looking at the attached LB Corella map from birdata (at I think10 minute
level rather than the one degree cells of the Atlasses) there appears to be a
rather high correlation between reports of outlier LB Corella reports (other
than Sinny metro area) and the watercourses of the Murray Darling system.
Possibly that is a coincidence reflecting the likelihood of towns being on the
rivers (or birders being on the rivers) but it does suggest to me that the
birds might have spread themselves up the system from Balranald(ish).
Martin
On Sat, Dec 19, 2009 at 10:03 AM, Geoffrey Dabb <> wrote:
Interesting about the corellas,
Sandra. Numbers might be unusual, but I’d suggest they are still in
their ‘normal’ range. In the below adaptations of the atlas
maps I’ve marked Deniliquin with a green star. Even in 77-81 that
was on the edge but within the natural extension. The great spread
further afield in 98-02 has been attributed to releases and escapes, and I
think that accounts for the birds in Canberra. By contrast the map for
the Little Corella would show a continuous extension. I think that is
reinforced by the large numbers that turn up here periodically. Therefore
if we were suddenly to get a hundred Long-bills I would say the resident
introductions had been augmented by an advance party from the riverina.
Another indication would be to watch carefully and see if they show a preference
for Australian Rules, western Victoria and the riverina having strong
traditional associations with that particular form of boot-ball.
From: sandra henderson [
Sent: Friday, 18 December 2009 9:19 PM
To: Cog line
Subject: [canberrabirds] spectacular gathering of corellas (not local!)
- and channel-billed cuckoo in Wanniassa yesterday
I'm
spending the night in Deniliquin, at my favourite motel by the
river. For the past hour there has been a huge flock of long-billed
corellas settling down for the night in the adjacent tall eucs. The
person in the unit 2 doors up estimates there are 5,000 in the flock.
Every now and again they all take flight together, calling loudly, circle a few
times then back into the trees - I'm guessing some trees have literally
hundreds of birds in them - all within 50 metres of my room - the noise is
deafening and the sight is amazing. now that its almost completely dark I
suppose they'll soon decide its time to sleep.
