Common Mynah Study

To: Philip Veerman <>
Subject: Common Mynah Study
From: Dave Torr <>
Date: Mon, 13 Aug 2012 15:05:19 +1000
Excellent response Philip - I have long learnt that newspaper articles on
subjects that I know something about (birds and computers)  are nearly
always wrong - so I assume the rest are as bad as well. I seem to recall an
article in The Age on birds on Mud Island in Port Phillip bay that invented
a new species of Egret....

Would be good to write to the paper with this detail - although they will
probably ignore it.

On 13 August 2012 14:44, Philip Veerman <> wrote:

> This on-line article Published in the journal PLoS One (see
> )
> is most unfortunate. If you read it at all, I recommend great scepticism.
> This study uses data from the Garden Bird Survey (GBS) but severely
> misrepresents the way the data were collected. For that and several other
> reasons, I believe this study is multi-flawed. I am the author of the book
> "Canberra Birds: A Report on the first 21 years of the Garden Bird Survey",
> (in short The GBS Report) which I regard as a fitting tribute to all those
> who have contributed to the Garden Bird Survey (GBS). This book is a
> detailed analysis of the history, methods and results of the GBS that has
> been run by Canberra Ornithologists Group (COG) in Canberra,  since July
> 1981. On a personal note, I am angry that this myna article was released
> without being checked and verified (by someone who knows, such as me) as a
> true representation of the data methods of the GBS.
> The GBS Report is cited in this on-line article but clearly was not
> consulted properly let alone understood. The article then goes on to make
> several major errors in understanding the data framework.
> The way it states the GBS was run (stating it as fortnightly surveys of 20
> minutes) is a nonsense. It is and always has been since 1981, data
> collected
> on a weekly grid, for unlimited time (i.e. up to 10080 minutes per week,
> even though many observer weeks would be only from one to 10 minutes of
> effort). This is clear from any one of the something close to 2000 GBS
> charts that have been printed, let alone the full description of the
> methods
> and history of The GBS Report. It says "a total of 74 492 surveys was
> undertaken in the survey area over 29 years". Not so. The GBS in its
> totality is ONE survey. 74 492 is simply the number of observer-weeks (up
> to
> year 29), which is a week on a chart with a record for at least one
> species.
> That is not a survey. They describe the survey area as 3.142 ha, as though
> all the contributors have uniformly selected the size of the area to 4
> figures of significance and all equally keep to that area for all species.
> The best that could be said is that observers variably set a survey area
> based on the recommended 100 metre radius, but as this is a volunteer
> survey
> and in the first 12 years this 100 metre radius instruction was very vague,
> this is far from consistent. There is little if any understanding of the
> geographic or time issues involved, or the way that the survey has evolved.
> The way they have used the data after subdividing the area geographically
> over time is I think ridiculous, given the way that distributions and
> numbers of observers has changed substantially over the years. There is
> little attempt to explain the wonky ideas proposed and used, such as why
> they translate a 100 metre radius to a square kilometre, as though habitat
> spread is even, which it is not and even if it is, it is highly
> questionable
> that every species has been equally counted to the same area. There is
> little attempt to justify the rationale behind the species chosen to be
> analysed. It seems unaware that there is a huge range of factors impacting
> separately or together on every species, that influence perceived changes
> in
> status (not just the addition of another species). Perceived meaning real
> and then as revealed after imposition of survey biases. I submit that the
> analysis is way over the top mathematically, doing calculations that go way
> beyond the real usability of the actual data. To call the article
> "Empirical
> Evidence" is way beyond the truth. At best all that can be said is that
> there is some correlations in time between the observed changes in the
> distribution and abundance of mynas and other avifauna. To an extent some
> of
> the analysis and conclusions are of interest.
> The SMH article mentions: the results show that even when taking into
> account the capital's urbanisation, the myna's arrival has reduced numbers
> of cavity-nesting birds such as the sulphur-crested cockatoo, crimson
> rosella and laughing kookaburra. Yes the Kookaburra has declined but the
> Sulphur-crested Cockatoo and Crimson Rosella have had consistent and
> significant increase in abundance throughout the period. The Eastern
> Rosella
> has been remarkably stable and the Red-rumped Parrot has been variable.
> How do these conclusions from the article make sense? "The abundance of the
> Common Starling appeared to increase after Common Myna establishment.
> Common
> Starling abundance declined throughout the survey period. We found no
> significant negative relationships between Common Myna establishment and
> Common Starling abundance." It is abundantly obvious that the Common
> Starling decreased as the Common Myna increased, that is described in The
> GBS Report as the most likely relevant interaction to any other species by
> the Myna. And what about the activities of Canberra Indian Myna Action
> Group
> Inc (CIMAG see and the culling program of Mynas
> being run and the huge reduction in Myna numbers that it has achieved in
> Canberra in recent years such that the rise in abundance has been halted
> and
> reversed. (So Carl we certainly do have a control measure.) Why is that not
> mentioned? Why is there no discussion of reversal of trends on other
> species
> occurring along with the success of this program?
> Lastly I will mention you can do any level of calculation you like with any
> set of numbers. I expect that this same analysis would find a strong
> connection between the numbers of Common Mynas and the number of mobile
> phones or that the numbers of Common Mynas had no impact on the number of
> vintage cars. The analysis might have a strong basis if all sites had been
> equally surveyed by the same methods for all species equally over all
> years.
> Not one of these aspects is correct. By all means read this article but
> with
> caution or with The GBS Report to properly explain the context of the data.
> Philip Veerman
> 24 Castley Circuit
> Kambah  ACT  2902
> 02 - 62314041
> Dear B-A,
> There is a piece in the Sydney Morning Herald's web site regarding a study
> on Common Mynah and their effects on native bird species.
> -pest-20120812-242v2.html   The study was based partly on data collected
> by
> the Canberra Ornithologist's Group. Now that we know they are a pest, it
> would be nice to come up with a control measure - that's the rub.
> Cheers,
> Carl Clifford
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