Press Release from Uni Melbourne ...
http://www.unimelb.edu.au/uninews/research/
22 April 2002
Farm dams threaten the survival of our rare birds
By Jason Major
Farm dams and other artificial stock water points are contributing to the
decline of rare bird species in Australia1s mallee and semi-arid grazing
lands, according to University of Melbourne research.
Pictured: Major Mitchell cockatoos drinking at a water trough in the
Gluepot reserve.
Previous research has shown that a proliferation of artificial water points
has led to overgrazing, soil compaction and changes in the composition and
structure of native vegetation.
Zoology PhD student, Mr Rhidian Harrington, has now completed his doctoral
research confirming that these water points also affect the number and
diversity of bird species.
"The rarer bird species are definitely declining," he says. "The reason for
the decline in rare species is mostly due to changes in vegetation caused
by stock using the water points, but an additional factor may be that the
many common birds now thriving around water points are excluding the rarer
birds through competition," he says.
The findings have implications for landholders wanting to set aside areas
for conservation or considering construction of dams or tanks to water stock.
"The best solution is to fence off remnant areas of bush, but on large
holdings, this is often impractical or costly. Landholders will need to
carefully consider the position of any new water points or where they
remove others," says Mr Harrington.
His study site is at the Gluepot Reserve, a 51,000 hectare grazing property
about 70km north-west of Renmark, South Australia. It was recently
purchased by the members of Birds Australia and is part of the Bookmark
Biosphere Reserve.
Mr Harrington found that water points in the reserve had effects on bird
species and numbers up to 10km away. At Murray Sunset this effect extended
to 20km, but he suggests water may have effects at even greater distances.
"For many of the rare birds, their optimal habitats appear to be further
than 20km from water," he says.
"Closing water points so that there are habitat areas more than 10km ? and
preferably over 20km ? away from water will help the rare bird species," he
says.
Mr Harrington recorded 113 species of birds during his study at Gluepot and
found 25 per cent of these needed to drink water for survival at some time
of the year. These 25 per cent, however, made up 75 per cent of the total
birds flying around at any time, and they were mostly common species of no
conservation value, like magpies, ravens, galahs and common bronzewings.
While research is needed, it appears that these common species may be
benefiting at the expense of the rarer species by outcompeting them.
"In the short-term, closing dams may cause a localised decline in the
numbers of bird species as some of the common water-dependent species
disperse to other water points," says Mr Harrington.
"Eventually, though, as the vegetation regenerates, the numbers and types
of species will increase as the rarer species return and have an
opportunity to build up numbers," he says.
Birding-Aus is on the Web at
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