The Common Myna: 'Is It Benign or Is It a Pariah?' Comment on Mike's message.

[Denis Wilson <>]

Hi Cog Chat line members

Now that the subject appears to be drifting to Pied Currawongs, I can offer the comment that the first records of breeding of Currawongs in Canberra of which I am aware, came from an "egg collector" (pers comm, as they say in official journals), in the early 1960s.

The location of that "first Currawong's nest and egg collection" was Telopea Park circa 1961. Telopea Park was one of the oldest established plantations of tall Eucalypts, in the early days of Canberra.

Subsequently they became established in Forrest, and then the ANBG as those areas developed enough tall Eucalypts for the Currawongs to breed in.

The supply of succulent nestlings in the ANBG is a matter of record, courtesy of the extensive studies of  Superb Fairy Wrens there by the ANU students.

But in my personal experience, it was the presence of established tall Eucalypts which enabled the winter-visiting Currawongs to remain in Canberra over the summer, in suitable breeding habitats. 

The suggestion of available high-protein food (notably nestlings of other birds) as the causal link risks putting the Chicken before the Egg - in my opinion. Two sides of the equation are necessary, I agree, but the thing which changed in or around 1960s in Canberra was the maturation of the early Parks and Gardens plantations of tall Eucalypts.

Denis Wilson

On Sat, Aug 11, 2012 at 11:14 PM, Philip Veerman <> wrote:

Thanks for interesting comments there from Mike, I pretty much agree with all of that. We need to be cautious though. The Myna has never reached the situation of being present in Canberra in enormous numbers, enough to really have a big impact (as appears to be the situation in other cities). That is substantially due to the reduction activity done (by CIMAG) as the numbers have started to get close to looking like they would soon be reaching that point.

 

Mike also mentions Pied Currawongs, although with an angle that is a new one on me. Hence summer breeding of currawongs in Canberra could be interpreted as a sign of a healthy avifauna that can now support the breeding of these birds. Could be something in that. I don't know. I had thought of the huge increase in the summer population - along with reduction in the size of their flocks in winter - as demonstrated so well in The GBS Report (graph on page 90 of the 21 year edition but not in the 18 year edition) -  is more due to the increased around the year availability of food (especially fruits and berries), that has allowed more Currawongs to survive through the year and maintain territories locally and thus be ready to breed.

 

Philip

 

-----Original Message-----
From: Mike Braysher [
Sent: Saturday, 11 August 2012 11:50 AM
To: 'Geoffrey Dabb';
Subject: RE: [canberrabirds] The Common Myna: 'Is It Benign or Is It a Pariah?'

Geoffrey is correct, the change in bird fauna cannot be attributed to Indian Mynahs based on the study and the data in the paper. At best all that can be said is that there is a correlation between the observed changes in avifauna and the distribution and abundance of mynahs. A well designed replicated experiment comparing treatment (areas with mynahs with areas without mynahs, would be required) - or a comparison of changes in avifauna at  sites where mynahs were greatly reduced in density to areas where there was no reduction. There have been many changes in Canberra's avifauna since I arrived in 1974, 6 years after the first mynahs were released. Since then mynah numbers increased but there were many other changes,. In 1974 currawongs were winter migrants - few bred in the city; galahs were rare, as were crested pigeons and corellas, while starlings and sparrows were very common with large flocks roosting during winter in Civic and Manuka as well as being common in the Jerrabomberra Wetlands and Tidbinbilla. There has been a massive change in the abundance of these species since then, changes that have coincided with the increase in mynahs. However, while these events are correlated, I doubt that anyone would attribute the changes in these natives to the increase in Indian Mynahs. I recall some work that David Purchase undertook in around his suburb of Macgregor from the 1960's (for those that do not know David, he was the Director of the national Bat and Bird Banding Scheme). David recorded a steady increase in the variety and density of many native birds after the suburbs were first settled. He postulated (correctly I believe) that as the suburbs aged there was a major increase in the quality of habitat and the availability of food  for native birds (both from exotic and native plantings). This is not  all that surprising as many new suburbs were built on old grazing land. I suspect that currawongs now breed in Canberra because of the availability of nestlings for their chicks (both native and exotic such as mynahs) although a replicated experiment would  be needed to test this. Hence summer breeding of currawongs in Canberra could be interpreted as a sign of a healthy avifauna that can now support the breeding of these birds.

 

Nevertheless,  I believe that the basic conclusion of the paper is correct, that there is little evidence that Indian mynahs are as damaging to native avifauna as was previously believed. Even the conclusion that mynahs have slowed the rate of increase of species such as sulphur cresteds and crimsons is dubious. Both are common and cannot keep on increasing at the rate they have been as they will eventually start to run out of resources causing the populations to slow and possibly decrease - even if mynahs were having an influence.

 

The crucial issue with managing invasive species is to focus on the desired outcome from management not on pest reduction per se. The question needs to asked, what are the social, production and/conservation outcomes that need to be addressed through management - decline in certain native species, reduced production from orchards or social amenity? Then we should ask what are the factors influencing these desired outcomes from management, invasive species (weeds and pest animals) are likely to be one factor but invariably there will be other factors such as loss of the quality of habitat due to clearing, over grazing (by natives and exotics), impact of global warming and reduced rainfall, or changes due to increased firing of habitat for hazard reduction. Too often in the past we have take\n the easy route and quickly blamed exotic species for all the ills without stepping back and taking a broader perspective. Sure many invasives cause damage and I wish that they were not here, but if we put all our eggs in one basket and focus only on exotics, then we may still lose native species due to other factors. To illustrate this, David Pridell showed that a small percentage of mature foxes knew when mallee fowl chicks were about to hatch and they predated heavily on them. Following intensive fox poisoning there were more chicks hatched but most did not reach maturity. Further investigation showed that the seeds of native grasses that the chicks fed on were rare due to past grazing. If he had stopped at intensive fox management, then there would still have been no recovery in mallee fowl. There are many other similar examples.

 

For more information on how best to manage the damage due to invasive species, members might like to download and read the recently released ACT Pest Animal Strategy 2012 - 2020: http://www.environment.act.gov.au/environment2.

 

Mike Braysher

 

From: Geoffrey Dabb [
Sent: Friday, 10 August 2012 2:43 PM
To:
Subject: FW: [canberrabirds] The Common Myna: 'Is It Benign or Is It a Pariah?'

 

I have read this article 3 times and I am unable to see how it shows the Common Myna is responsible for a decline in small birds.  Small birds may have declined over the period but where in the opaque maths is it shown that the myna must be the reason?  Below is a random cut/paste of articles on overall bush-bird decline, including one suggesting the NOISY MINER (expanding in Canberra) is a reason.  [In fact, as I read the piece, it suggests that small birds are INCREASING LESS RAPIDLY in Canberra gardens because of the myna] 

 

 

THREATENED AND DECLINING WOODLAND BIRDS IN THE NEW... 

www.lrwg.com.au/downloads/.../WEDecliningBirdReport99Reid.pdf

File Format: PDF/Adobe Acrobat - Quick View
by JRW Reid - 1999 - Cited by 110 - Related articles
standout Declining bird species in the SWB. All but two of the 20 Declining species are passerines or 'typical bush' birds. This contrasts with the 38 Threatened ...

1.   Native bird populations declining rapidly - The 7.30 Report - ABC 

www.abc.net.au/7.30/content/2009/s2720637.htm

21 Oct 2009 – It is well documented bird populations are in serious decline across the ...LISA WHITEHEAD, REPORTER: The Australian bush without the call ...

2.    [PDF] 

The effect of Noisy Miners on small bush birds: an unofficial cull and ... 

www.une.edu.au/ers/staff-profile-doc-folders/.../debus-n-miner.pdf

File Format: PDF/Adobe Acrobat - Quick View
by SJS DEBUS - Cited by 3 - Related articles
... in each time period. Totals for small (<120 g) bush birds, mostly ... are a major contributor to the local decline of many woodland birds. The results also affirm ...

3.   Bush Birds 

www.sopa.nsw.gov.au/our_park/environment/.../birds/bush_birds

Although none of the bush bird species at Sydney Olympic Park are listed under threatened species legislation, many bush birds are in severe decline across ...

4.    [PDF] 

facing 

www.cse.csiro.au/research/documents/ecosbirdsextinction.pdf

File Format: PDF/Adobe Acrobat
Australia's bush birds are in trouble. Only one ... regions are in decline, and more species will vanish if ... causes and extent of bird declines across the southern ...

5.   No birds in the bush 

www.birdlife.org › BirdLife News › News Archive Search

01-06-2010. Australia's woodland birds, including many species generally regarded as common and widespread, are declining at an alarming rate according to ...

6.    [PDF] 

AUSTRAL

 

-- 
Denis Wilson
"The Nature of Robertson"
www.peonyden.blogspot.com.au