John
Canberra is a hostile environment for mynas and, as you observe,
mynas are adapting by changing their behaviour. Some of the more
radical behavioural changes have taken place in less than a decade.
For example, our control programs remove many unwary, inexperienced
birds from each new cohort and educate the survivors about the
hazards of commensal living in Canberra. In this remarkably short
time, control measures have selected for cautious, cryptic behaviour
in experienced breeding mynas and in their offspring. Where once
mynas were commonly seen and heard in gardens and in busy public
places, they now succeed by conducting much of their activity out of
the public gaze. Because they are less conspicuous, particularly
while foraging, we are led to conclude that they are less common.
In most areas, the casual observer would be aware of mynas in the
landscape only between December and March when the new cohort of
dispersing juveniles forms conspicuous foraging groups near
successful nest sites.
Further adaptations can be seen in their choice of nest sites.
Viable cavities in the urban environment are limited by our active
management of artificial structures and garden vegetation. Mynas
choose the nest cavities least likely to be disturbed by us. In
many parts of Canberra the least disturbed cavities are in the
natural hollows of remnant eucalypts scattered through the suburbs
and in adjoining reserves and rural leases. The mynas' choice has
negative impacts on at least three local native hollow-nesting
birds.
Canberra mynas are already well adapted for nesting in the deep
hollows of remnant eucalypts, and they are beginning to make use of
shallow cavities in some of the many eucalypts planted widely in the
1960s - 1980s and now maturing. I have mapped 152 active nest sites
this breeding season (see http://www.feralscan.org.au/mynascan/map.aspx).
Excluding 39 cases where the nest entrance was obscured, my
sightings break down as follows:
| Nest type |
Number |
% |
| Remnant hollow |
72 |
63.72 |
| Dense vegetation |
20 |
17.70 |
| Structure |
17 |
15.04 |
| 1970s hollow |
4 |
3.54 |
| Total |
113 |
100.00 |
It seems that the mynas dispersing into the countryside around
Canberra each season are increasingly likely to be pre-adapted for
avoiding humans and for nesting in native vegetation. Your
observation that their behaviour is increasingly like that of native
woodland birds is a neat summary.
Elsewhere I have mentioned some other aspects of research and myna
control policy in need of attention:
https://db.tt/yCGbXEIa
https://db.tt/xiRx9YEc
https://db.tt/1HVRE0p3
Regards
Daryl
On 27/01/2014 5:12 PM, John Harris
wrote:
Several weeks ago I reported a myna event here in Nicholls. I
had not seen mynas much at all for some months which was quite
pleasing, although blackbirds are increasing. Then one day a
surprising mixed flock of about 100 ‘pest species’ made a huge
commotion – about 50 mynas, 30 starlings and 20 blackbirds.
While the whole flock eventually took off to the north, since
then myna numbers have greatly increased here which is a worry.
An interesting but worrying observation is the changed
behaviour of the mynahs. When we had a lot here a few years ago,
they were mainly encountered in my garden, digging and generally
being a nuisance. Although the numbers are now even greater,
after the lull I mentioned, the mynas are behaving more like
native woodland birds. They are nesting on Mt Percival and I
have seen them diving into Ginninderra Creek to drink (like Red
Wattlebirds do) and acrobatically catching insects in the air
(like the Flycatchers and Fantails do.)
This is very anecdotal and unscientific but it worries me
that they are showing such adaptive skills.
John
John
Harris
Rev Dr John Harris,
36 Kangaroo Close,
Nicholls, ACT 2913
AUSTRALIA
P:
61-(0)2-62418472
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