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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