Kate Grarock (and colleagues) has just published some of the results of their Canberra Myna research in the latest issue of Austral Ecology (assistance of Ormay, Lashko, Allan and other COG members in acknowledgements) –
Robin Hide
Grarock, K., C. R. Tidemann, J. T. Wood and D. B. Lindenmayer (2014). “Are invasive species drivers of native species decline or passengers of habitat modification? A case study of the impact of the Common Myna (Acridotheres tristis) on Australian bird species.” Austral Ecology 39(1): 106–114.
Keywords: driver-passenger model; Indian myna; introduced species; pest management; Sturnus tristis.
Abstract: Habitat modification and invasive species are significant drivers of biodiversity decline. However, distinguishing between the impacts of these two drivers on native species can be difficult. For example, habitat modification may reduce native species abundance, while an invasive species may take advantage of the new environment. This scenario has been described as the driver-passenger model, with ‘passengers’ taking advantage of habitat modification and ‘drivers’ causing native species decline. Therefore, research must incorporate both habitat modification and invasive species impact to successfully investigate native species decline. In this paper, we used the common myna (Acridotheres tristis) as a case study to investigate the driver-passenger model. We investigated changes in bird abundance, over 2 years, in relation to different habitat types and common myna abundance. We hypothesized that the common myna is both a passenger of habitat change and a driver of some bird species decline. Our results indicated that the abundance of many native species is greater in high tree density nature reserves, while the common myna was uncommon in these areas. Common myna abundance was almost three times higher in urban areas than nature reserves and declined rapidly as tree density in nature reserves increased. Our findings indicated that the common myna is primarily a passenger of habitat change. However, we also observed negative associations between common myna abundance and some bird species. We stress the importance of simultaneously investigating both invasive species impact and habitat modification. We suggest habitat restoration could be a useful tool for both native species recovery and invasive species control. Understanding the drivers of native species decline will help inform impact mitigation and direct further research.
Notes: Supporting Information at:
http://onlinelibrary.wiley.com/doi/10.1111/aec.12049/suppinfo
Appendix S1. List of species observed.
Appendix S2. Significant explanatory variables for restricted maximum likelihood analysis.
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Mynas using woodland trees near the suburbs is not a new phenomenon. I remember groups of Mynas in woodland trees in the Snow Gums area in the Aranda Bushland and another south of the William Hovell Dr x Bindubi St intersection long before Myna trapping started in Aranda/Cook both about 1k from the nearest houses. I did not investigate if they were nesting but I suspect they were.
A couple of years ago I noticed Mynas flying from Kaleen across the Barton Hwy to a hollow branch in a tall euc in Gungahlin Hill NR at frequent intervals. I feel sure they were feeding young although I don’t remember hearing the young.
The Mynas in the Aranda Bushland and near the W’m Hovell Dr x Bindubi St intersection disappeared after the Myna trapping started in Aranda and Cook. My guess is that the Mynas at those sites returned to the suburbs once the population pressure there was lifted by the trapping. There is a PhD in sussing this out I think.
Re the Mynas at Strathnairn. About 10years ago a pair of Mynas turned up on Smiths Rd at least 15k south of the nearest Myna population in the Lanyon Market area. (There were non at Tharwa and still aren’t). I suspect that when Myna populations get high in urban areas some fly off (along roads?) searching for settlements further afield to settle in.
Peter
With reference to John's Holt comments:
There's currently an active family group of Mynas at Strathnairn Homestead Gallery less than 2km to the west of Holt. Seven were taken from there by trapping but none have been targeted since, I believe.
It's very common driving along Drake Brockman Drive to the south of Higgins and Holt to see Mynas flying to and from the suburbs and the residual woody-grassland and paddocks south of Drake Brockman Dr. In other words the mynas are using tree hollows in the old paddock trees.
Rosemary
On 28/01/2014, at 12:23 PM, John Layton wrote:
Here’s my two bits worth re general observation of Common Mynas in & near our place.
A decade or so ago it wasn’t unusual to see flocks of 10 to 15, sometimes more. However for about the past four years we can go for several weeks and see nary a one, then groups of five or six will appear for a few days before another hiatus.
I somehow suspect observers in other areas of Holt and nearby suburbs may notice a different pattern. (Shrug.)
