Hi Keith
The Flying-fox hypothesis sounds good but again Australian Field
Ornithology, in the issue following the one with the evidence that POs are
really increasing in suburban Sydney, has a possible response.
In Vol 22.2 (June 2005) there is an article on the "Diet of a Powerful Owl
Roosting in the Royal Botanic Gardens, Central Melbourne" by Peter
Menkhorst, Rex Buckingham and Richard Loyn.
For 6 months in 1989/90 Rex Buckingham collected pellets (at least 73) from
under the owl's roost. His widow (Rex passed away in 1999) gave them to PM
for analysis.
Of the total 91 prey items that were identified (by Barbara Triggs) only one
was a Flying-fox! This was despite there being up to 20,000 present in the
RBG camp in the 1980s. By contrast rats constituted 31% of items and
possums 52%.
The article cites studies by Kavanagh of 47 sites in southeastern Australia
which included one where flying-foxes were 77% of prey items, and one at
Gordon in Sydney having flying-fox remains in 26% of samples. Further his
research, and that by Pavey, apparently shows that there is no link between
the presence of flying-foxes and of POs.
The conclusion is that POs are adaptable and may not prefer Flying-foxes in
their diet.
Michael Norris
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