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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