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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