I think this is a great case study for the conservation of sedentary and
habitat restricted species.
The distance between the southern end of the Great Dividing Range and the
beginning of the otways couldn't be more than 100-150km apart. And the
minimum distance that a species would have to travel over an 'inhospitable
biogoegraphic barrier' would be about 50-70km.
For such a short distance, it seems that no habitat restricted species has
been able to make the journey in over 6,000 years! (probably extending to
a few hundred thousand years)
The land clearing that has occurred in the last 200 years in the Great
Dividiing Range has introduced expanses a lot bigger than 50km. So what
strains are we putting on genetic diversity of such species???
Peter
"Lawrie Conole" <>
Sent by:
12/03/2008 11:31 AM
To
"Birding Aus" <>
cc
Subject
[Birding-Aus] re: Otways- Eastern Whipbird, Superb Lyrebird?
Regarding the absence of a range of typical east coast wet forest birds
from
the Otway Ranges in SW Victoria, you need to think back in time - way back
in time! The landscape has changed a lot in the last few hundred thousand
years - particularly in configuration as well as nature of habitat blocks.
One of the most important factors in differentiating SW Victoria's
avifauna
from the otherwise continuous East Coast/Great Dividing Range would have
to
be the enormous and inhospitable biogeographic barrier called the
Victorian
Volcanic Plain. Consider that Red-browed Treecreeper occurs all the way
west to near Daylesford on the Great Divide; Superb Lyrebirds, Pilotbirds,
Large-billed Scrubwrens and Lewin's Honeyeaters peter out around the west
end of the Kinglake Plateau and Mt Disappointment - all of these contained
within the relatively continuous Great Dividing Range wet forests.
Pilotbirds are more or less replaced by Rufous Bristlebirds in the Otways.
It would be very surprising indeed if there were anything functionally
"wrong" with the Otway forests to explain the mildly depauperate avifauna
-
more likely it's simple species turnover from relative isolation. Some
typical wet forest birds are still there (residents and migrants - Satin
Bowerbird; King Parrot; Gang-gang; Flame, Pink & Rose Robin, Rufous
Fantail,
Brush Cuckoo, Bassian Thrush, Olive Whistler, Satin Flycatcher) - and some
continue on into other relict populations even as far west as the South
Australian border (Rose Robin, Gang-gang Cockatoo, etc.). Some wet forest
mammals occur well west in isolated outliers of the Great Dividing Range
through central Victoria (Mountain Brushtail Possums at Mount Cole near
Ararat; various species in the Grampians and Otways). All looking like
bits
and pieces of a formerly more extensive wet forest landscape.
There are in fact some apocryphal stories about odd lyrebirds seen in the
central Otway Range (e.g. one during Atlas I on Cape Otway, May 1977 -
from
Pescott 1983), but nobody seriously believes these are representative of
relict local populations - rather they are misidentifications, wishful
thinking, or escaped/liberated captive birds.
--
++++++++++++
Lawrie Conole
28 Reid Street
Northcote, VIC 3070
AUSTRALIA
lconole[at]gmail.com
0419 588 993
REFERENCE
Pescott, T. (1983). 'Birds of Geelong.' (Neptune Press: Newtown).
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