I think Tim Lowe had something to say about this sort of thing in his latest
offering ...
http://www.theage.com.au/text/articles/2002/06/24/1023864552756.htm
Imported smorgasbord attracts bats
Date: June 25 2002
By Melissa Fyfe Environment Reporter
Scientists at the Royal Botanic Gardens have solved the puzzle of why the
grey-headed flying fox - not a traditional resident of Melbourne - has settled
in the gardens and remains in the city in huge numbers.
It seems that the flying foxes keep hanging around because Victorians have
planted thousands of New South Wales and Queensland trees that provide the
winged mammals with a smorgasbord of food.
Before European settlement, Melbourne had only 13 species a flying fox could
eat. Now there are 100 species, according to a two-year study by the Australian
Research Centre for Urban Ecology, based at the Botanic Gardens.
The centre found that local councils had planted more than 315,000 NSW and
Queensland street trees. Add to this the non-Victorian trees in parks and back
yards and you have a feast of eucalypt nectar and fruit.
Before 1983, the grey-headed flying fox - a type of bat - was never known in
Melbourne in numbers larger than 100, and the most southern bat "camp" was in
Mallacoota. They preferred Queensland and NSW.
"Humans have created a new forest which is a year-round and abundant source of
food for grey-headed flying foxes," said the centre's ecologist and director,
Mark McDonnell.
Associate Professor McDonnell said the planting of this "new urban forest" of
non-Victorian trees - such as the spotted gum, red flowering gum, lemon-scented
gum, Moreton Bay fig and lilly pilly - should be stopped.
"If we are going to manage the flying foxes in Melbourne, it would be useful to
reduce the amount of food and resources available to them," he said.
Each evening thousands of flying foxes leave the gardens to eat in the suburbs,
but Professor McDonnell and his team also had to work out why the animals so
stubbornly insisted on choosing the Botanic Gardens as their home (5000 flying
foxes live permanently in the gardens, but numbers swell to 24,000 in summer,
creating a smelly mess and destroying plants). Bat camps are typically near
water, often have dense vegetation with an intact canopy, are secluded and are
in a gully: all features of Fern Gully, their tropical rainforest home in the
gardens.
The relocation of up to 75 flying foxes will begin next month after Planning
Minister Mary Delahunty last week approved a key planning scheme amendment for
Horseshoe Bend in Ivanhoe. The move follows last year's controversial cull and
federal listing of the animal as vulnerable.
In trees at Horseshoe Bend, the Department of Natural Resources and Environment
will build three four-metre-tall cages for the flying fox mini-colony. It is
hoped other bats will be attracted to the site as an alternative camp to the
gardens.
"Every flying fox we attract to that site is one that is attracted away from the
gardens," the department's flora and fauna manager, Dr Robert Begg, said. "It is
really quite a novel way of managing wildlife issues in an urban environment."
When the cages are ready, staff at the gardens will create a variety of noises
to disturb their unwanted guests.
Professor McDonnell said Melbourne's thousands of NSW and Queensland trees meant
the city's ecology had changed. It meant, for example, that rainbow lorikeets
and possums prospered.
.
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