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Ian,
Absolutely. The Common Myna has
"mushroomed" in Canberra during the same period, from being rare at
the start of the survey (1981) to omnipresent now. Of course it is hard for
observational science to demonstrate cause and effect (and probably impossible
to prove it). The Common Myna probably competes only with with the Common
Starling for both food and nest sites. The relationship of both to the
House Sparrow and Common Blackbird abundance changes over the time is
harder to work out. Then there is the changes (mostly drastic increases) in the
larger parrots, whilst the Eastern Rosella is stable & Red-rumped Parrot has
declined. All facts and figures are available to anyone who wants
them.
Philip
-----Original Message-----
From:
Ian Montgomery <>
To:
birding-aus <>
Cc:
Philip A. Veerman <>
Date:
Friday, 12 April 2002 12:37
Subject: Re: [BIRDING-AUS]
Declines in common species
On Friday, April 12, 2002, at
11:51 AM, Philip A. Veerman wrote:
From the 18 years
of continuous GBS data in Canberra, the Goldfinch has shown a decline
but that is not easy to interpret. It is largely based on the fact that
it was especially abundant in 1981-82. That being the first year of the
GBS, it is impossible to know whether it was just an odd year. After
1982-83 it has been basically stable here. Unlike say the Starling and
House Sparrow, whose abundance has crashed over the same period.
Philip
I
wonder whether Starlings and House Sparrows have suffered from competition
with Common Mynas. It would be interesting to see if there were any
correlations between changes in range and abundance of these 3 species. It's
my feeling that Starlings suffer when Mynas move
in.
Cheers,
Ian
**************************************************************
Ian
Montgomery, Townsville, North Queensland,
Australia
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