I think Canberra would make a very good study for the effects of
climate change on bird distribution because of the Canberra
Ornithologists Group records and database and because of the fact
that Canberra is on the borders of diferent ecological zones
(coastal/inland, lowland/highland).
My own feelings after 16years of residence in Canberra are the
general impoverishment of the bird fauna. The wet mountains seem now
to be drier and their distinctive birds harder to find, the lowland
woodlands also seem drier and many species that used to be easy to
find (Hooded Robin, Diamond Firetail and Brown Treecreeper) are now
more difficult. Conversely drier zones spp such as White-browed and
Masked Woodswallow are now more common.
The last 20-15 years have seen a drying trend in the Canberra area,
with autumn rains in particular not being anywhere near historical
levels.
You would have to disentangle any trends that could be due to causes
other than global warming, eg
1. More western vagrants could be spotted and recorded due to there
being more observers and a better recording system than in the past.
This same reason might also underestimate the decline in bird spp (i
there are fewer birds, but a greater percentage of them are being
observed and recorded).
2. The Canberra bushfires of January 2003 destroyed much of the
vegetation of the mountain forests, and although it is regenerating
it wil be many years before the forest are back to true wet forests.
Of course, you could say the extent and destructiveness of the fires
was due to the drying trend, which you could also say is due to
global warming. But how do you account for one off, stochastic events
in this sort of analysis, as opposed to long-term gradual changes?
3. Any changes as a result of global warming would be against a
background of general habitat fragmentation, alternation and
destruction that has been the case since Europeans arrived in Australia.
John Leonard
On , Gary Davidson <> wrote:
I cannot add to data on Australian birds, but some might be
interested in similar observations from western Canada, particularly
British Columbia. A few years ago, some concern was expressed about
a few species common in southern BC - their numbers were declining.
It was not until later that it was discovered that there was a
corresponding increase in their numbers further north. Their numbers
may not have been declining after all, just shifting northward. This
is all fairly recent, so there is not much in the way of hard data
yet, just birders' observations. As I recall Common Nighthawk was
one of the first species. There is one biologist/geographer in
Vancouver doing some research on this topic and I understand he does
have some fairly convincing evidence of range shifts, which he is
linking to climate change. I don't know if he has published anything
yet, but I can make some enquiries. If anyone is interested in
further reading on
this topic in the northern hemisphere, contact me privately and I'll
see what I can find out.
Gary Davidson
--- On Wed, 1/27/10, James O'Connor >
wrote:
From: James O'Connor >
Subject: RE: [Birding-Aus] climate change & bird distribution
To: "Greg Roberts" >,
"" >
Received: Wednesday, January 27, 2010, 9:34 PM
Hi Greg,
Thanks for this post: these are very interesting observations about
potential range shifts which, as you point out, haven't received a
lot of attention. I would be interested to hear from other observers
of other potential range shifts or contractions, especially
latitudinal and altitudinal shifts. We're particularly interested in
the fragmentation of populations in eastern Australia along the GDR,
but all observations of this kind would be welcome as a starting point.
We have used the Atlas to identify or confirm range shifts and
contractions in several species (eg Australasian Bittern and Crested
Pigeon), but Greg's observations are news to me, and I am sure there
are other examples.
Cheers,
James
Website address: http://www.birdsaustralia.com.au
Atlas website: http://www.birdata.com.au
ABN: 87 004 076 475
Australian Partner of BirdLife International
-----Original Message-----
From:
On Behalf Of Greg Roberts
Sent: Wednesday, 27 January 2010 7:10 PM
To:
Subject: [Birding-Aus] climate change & bird distribution
There has been a good deal of material about the southern extension
of range
of more northerly species which may be due to climate change. Less
has been
said in Australia at least about the converse - the possible
shrinkage of
range of more southerly species.
South-east Queensland is the northern limit of range of quite a few
southerly species, so here would presumably be a good place to look.
I have found, going through my old notes, that Crimson Rosellas in
southeast
Queensland were, in the 1970s, once widespread and common in places
where
they are now scarce or absent - for instance, about Little Yabba and
Booloumba creeks in the Conondale Range. The species is still common
in high
mountain, high rainfall sites such as the Border Ranges, but there
is little
doubt in my view that it has declined sharply in numbers elsewhere in
the
region.
In similar vein, I believe populations of Satin Bowerbirds have fallen,
especially at lower altitudes. South-east Queensland is the northern
limit
of range of the south-east Australian populations of both Crimson
Rosella
and Satin Bowerbird, though both species have disjunct populations
in north
Queensland. I do not know if anything is happening with their
populations up
there.
A third species, the Red-browed Treecreeper, does not occur north of
southeast Queensland. I believe its numbers have also dropped sharply in
this region. It was formerly a regular site, for instance, in the
Blackall
and Conondale ranges, but it seems to be much more scarce there today.
Food for thought.
Greg Roberts
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