>Most introduced birds don't do well. In Australia and I presume elsewhere
>a great number of accidental and deliberate bird introductions fail.
>We should be also careful about judging the success of an introduction
>on human scales. Some introductions might take hundreds or thousands
>of years to fail.
You raise some very good points Andrew. Too often we address such issues
on a time scale according to our terms of reference and not according to
the actual evolutionary events occurring in nature. Another point (often
over-looked) is that extinction is a natural phenomenon which is well
recorded in fossil layers. The issue is really our awareness of the
consequences of events both past and present.
>a) They successfully exploit human-modified habitats. Much of Australia
>has been modified in the last two hundred years creating new habitats.
>Species that have exploited these have increased their range
>and numbers. For example, Galahs were found in modest numbers
>along northern bird courses, they are now abundant through most of
>Australia.
I agree this category accounts for many of the established "feral" and
"ectopic" bird populations. It is silly to consider the range of bird
species (both native and introduced) as static. A trivial example : The
NSW National Parks and Wildlife Service used to, and may continue to,
insist that galahs and Cacatua spp. cannot be released east of the Great
Dividing Range. Why? It causes a headache for vets in the Sydney region
when they have to explain to the public that a perfectly well rehabilitated
bird cannot be released back into the area that it was found... It is a
long drive to Bathurst!
Shane Raidal
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