We can certainly back-up Con’s observation.
On our property here in Wamboin, over many years ours and the surrounding
properties had many thistles, and consequently goldfinches were quite
common.
In recent years, through a combination of extended drought periods and more
affirmative action in removing thistles by us and our neighbours, goldfinch
numbers have dwindled to the point where sighting one is a rarity.
Coincidently, we have just discovered a large thistle with flowers and
seeds in our garden, and yesterday this bird was taking full advantage of our
laxness in removing it:
David
From:
Sent: Friday, January 25, 2013 9:43 AM
To:
Subject: Re: [canberrabirds] goldfinches
A systemic change over the last forty years has been
the introduction of the widespread use of herbicides to control thistles in
pastures. If thistles are being targetted, farmers will get to them before they
flower and set seed.
It is many years since I have experienced the clouds
of wind-blown thistledown that were quite common when I was a child.
If
there is a direct relationship between the Goldfinch population and the quantity
of thistles then my suggestion would be that, other variables being constant,
the Australian Goldfinch population has probably declined significantly over the
last half century or so.
Con
