On Fri, Nov 16, 2007 at 09:28:24AM +1100, Stuart wrote:
> I believe the planting of exotics such as May, Privet and craterous sp has
> provided winter berry food for first year Currawongs with resultant increase
> in survival rates and population. This has provided the CBC?s with a
> significant increase in hosts
I'm not sure change in host populations explains the increase in
Channel-billed Cuckoos. Reading HANZAB there is very little data
about CBCs so you can only speculate but my feeling is that hosts -
currawongs, ravens and magpies - have always been present along the
coast between Sydney & Melbourne in sufficent numbers so as to not be
a limiting factor for CBCs. My guess is that changes in food supply
is a more significant factor. I can point to one piece of evidence.
Figbirds diet overlaps with CBCs and like them Figbirds were rare in
Sydney 50-60 years ago and are now conspicuous. Also Figbirds show an
expansion south between the 2 Atlases - more obvious than CBCs.
Andrew
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