Dear Brian and others,
At present I'm working on Bell Miners down in Melbourne, although significantly
smaller colonies than those at Merimbula (on matters other than habitat
degredation). However, as the story mentioned there is scant evidence that Bell
Miners actually cause dieback. True, they are often found in association with
areas affected, hence the catchy acronym BMAD (Bell Miner associated dieback).
The large-scale removal currently underway is an experimental opportunity to
test some of these ideas, however it is still only a sample size of 1 (albeit a
large one!). A PhD student at La Trobe University, Amada Dare, is currently
doing some work along with the gov organisations mentioned in the story on this
topic.
Personally, I don't believe BMs cause the problem, though they are likely to
probably make it worse. I think it is much more likely that they move to areas
already under stress and thus already high in psyllid infestation. Other
factors such as soil fungi and changing water flow patterns are probably just
as likely to blame. Noisy Miners have similar associations, though tree health
seems less affected. Both species significantly reduce avian diversity, however
this 'problem' is much older than the apparent recent trend for increasing
dieback levels. In any case good places to start for those interested in
looking at the scientific literature on the topic could start at:
Clarke MF, Schedvin N, 1999. Removal of bell miners Manorina
melanophrys from Eucalyptus radiata forest and its effect on avian diversity,
psyllids and tree health. Biological Conservation 88:111-120.
Ewen JG, Crozier RH, Cassey P, Ward-Smith T, Painter JN,
Robertson RJ, Jones DA, Clarke MF, 2003. Facultative control of offspring sex
in the cooperatively breeding bell miner, Manorina melanophrys. Behavioral
Ecology 14:157-164.
Grey MJ, Clarke MF, Loyn RH, 1997. Initial changes in the avian
communities of remnant eucalypt woodlands following a reduction in the
abundance of noisy miners, Manorina melanocephala. Wildlife Research 24:631-648.
Grey MJ, Clarke MF, Loyn RH, 1998. Influence of the Noisy Miner
Manorina melanocephala on avian diversity and abundance in remnant Grey Box
woodland. Pacific Conservation Biology 4:55-69.
There are other papers by Mike Clarke and also Richard Loyn on the topic, most
of which are cited in these.
Happy birding,
Paul
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr Paul G. McDonald
Department of Zoology
La Trobe University
Bundoora, Victoria 3086
Australia
Ph: + 613 9395 3253 Fax: +613 9395 3150
<>
http://www.zoo.latrobe.edu.au/Staff/mfc/pgm/
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