Declines in common species

To: "Ian Montgomery" <>, "birding aus" <>
Subject: Declines in common species
From: "Philip A. Veerman" <>
Date: Fri, 12 Apr 2002 12:49:33 +1000
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. 
-----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.

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.


Ian Montgomery, Townsville, North Queensland, Australia
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