G'day Everybody,
Firstly, immense thanks to everyone who has helped me with my research. I am
very grateful and so are the Brolgas and their friends.
I have just about finished field work and have much analysis to do but here
is a rough preliminary summary.
The Brolga (Grus rubicundus) in the NSW and Victorian Riverina:
At best, there are around 250 individuals remaining with a fairly well
documented decline in distribution and abundance. There are at least four
distinct subpopulations within the Riverina. It appears the Brolga is now
virtually extinct east of the Hume HWY from Sydney to Melbourne and only
rarely recorded any further west than Kerang. They are now restricted to the
area roughly bounded by Kerang, Wanganella (north of Deniliquin),
Jerilderie, Narrandera, Wagga, Albury, Wangaratta, Nagambie and Dingee.
Intensive irrigation areas, such as that around the Leeton and Griffith
region, can support good numbers of Brolga during the flocking season but
provide little or no opportunities for breeding and large numbers leave
these areas with the onset of the breeding season and Winter rainfall. NOTE:
There are brolgas found in southwest Vic. (+-750), including the southeast
of SA as well as scattered pairs through central NSW around towns like West
Wyalong, Forbes, Condobolin and Trangie. It is not until you hit the
Macquarie Marshes and right across northern NSW though (eg. Tibooburra,
Wanaaring, Bourke, Moree and Lawrence), that you start getting into the
hundreds and thousands found throughout QLD.
Thanks to birding aussers and the many other people who have helped me,
about 25! wetlands where nesting was attempted, were identified. Most nests
monitored hatched young, but the vast majority of chicks disappeared within
the first fortnight after hatching. A long lived species need not be
regularly successful but Riverina Brolgas have about 1/5 (2% compared to
about 10%) of the annual recruitment of brolgas across northern Australia
where foxes are absent and wetlands remain relatively intact. Adequate water
depths in a wetland (25cm+) throughout the breeding season (preventing or at
least reducing fox predation pressure) and sufficient native waterplant
communities for both cover and food appear critical for nesting to occur and
for it to be successful. Canegrass (Eragrostis australasica) and smaller
spike-rushes (Eleocharis), principally E. plana are the two most important
wetland plants for brolgas and also support a myriad of other species.
Wetland sites that brolgas used during the breeding season had a much higher
bird diversity than randomly selected control sites. 140+ species were
recorded, all but two or three at brolga sites, which is not bad for one
type of ecosystem - wetlands. About a quarter of the 60 brolga sites visited
during the breeding season also supported Australasian Bittern, now listed
as Vulnerable globally (Garnett & crowley 2000) with a total population
estimate, albeit a wild one, of only 2500. Also at about a quater of the
sites, Baillon's and/or Spotted (Australian) Crake were recorded. These and
other brolga sites visited supported other noteworthy species like Painted
Snipe, Little Bittern, Glossy Ibis, Wood Sandpiper, Blue-billed Duck,
Freckled Duck, Caspian Tern and Gull-billed Tern. The Brolga is highly
regarded by farmers as an integral part of Australia's wildlife heritage.
Brolgas are easily identified and conspicuous, relatively widespread and
well-known. The conservation of Brolga habitat will benefit a wide range of
other waterbirds and i personally recommend the use of the species as a
flagship (charismatic) for shallow wetland conservation.
Thanks again to everyone for their help!
Matthew Herring
School of Environmental and Information Sciences
Charles Sturt University
Albury 2640
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