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In regards to Lawrie Conole's question on Chestnut-breasted
Mannikins in the the Melbourne area, I've also have often wondered as to the
cause of this influx in the late Sevnties/early Eighties.
I saw a single Chestnut-breasted Mannikin at Seaford
Swamp in June 1980. Then some time in 1981 I came across three. At the beginning
of 1983 Peter Lansley discovered a huge flock at Seaford which if memory serves
me correctly was of thrity birds, but it may have been more. This flock hung
around for a couple of months and then disappeared. The bird has never been seen
at Seaford again.
Around the same time Mannikins were fairly regularly reported
in not only areas throughout Melbourne's Eastern Suburbs but there were also
reports from rural districts such as Yellingbo, Koo-Wee-Rup and even Tarra
Valley which is around 200 km from Melbourne.
The accepted wisdom was that these were feral populations that
bred up. But why did they then disappear? As far as I know there have been very
few, if any records since the mid-Eighties. As the 82-83 period was one of
severe drought in Eastern Australia could the influx of records at this
time could have had more "natural" origins of birds displaced from the drying
out of habitats further north?
Does anyone know how fast these birds breed? Perhaps the
Seaford flock were the direct descendants of those couple of birds I had seen a
year or two earlier. Is this sort of population explosion likely for such a
species?
Speaking of Seaford Swamp, last week (Thursday 17th) I joined
Chris Tzaros of Birds Australia for the monthly Melbourne Water census. Thanks
to recent record rainfalls water levels were still very high which ensured
plenty of diversity with 66 species being recorded.
Unfortunately the high water levels meant less wader species
though there were 170 Sharpies and 60 Black-winged Stilts. This will be the
first time in at least eight years that the swamp hasn't virtually dried out by
this time of year.
Sean
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