interesting Chas, that you should mention Australia.
Western Australia have a huge problem with Rainbow Lorikeets (sp)
As you have mentioned, they cull problem flora and fauna ie non Western Aussie native anything.
They trap/net/shoot the lorikeets in thier thousands, but the problem just keeps expanding.
Why.
The lorikeets original colony site is in the car park of Perth Airport. Theres thousands of them there, the noise is deafening.
The nature conservancy people cant do too much about these, imagine if tourists arrived and the first impression of Australia was seeing these magnificently beautiful birds being shot willy nilly
These ring necks here need controlling, end of.