The main thing that can be said about the long term trend for Pied
Currawong abundance in the GBS results is that there is no trend. The
values of the correlation coefficients for linear and polynomial
trends for 21 and 26 year results for the species range from just over
0.1 to nearly 0.3. These are well below the values that would
indicate a trend significantly different to zero.
I have attached a graph showing A values by week (months are difficult
since the weeks don't all start and finish at the bginning/end of
months) for 21 years and later years. This clearly shows a flattening
of the seasonal distribution in the recent past with more birds in the
warmer months and less in the colder months. There has been previous
correspondence on this list (last year some time) about the reduced
frequency of the huge flocks seen (particularly in the Weston area) in
the early years of the Survey.
Martin
Pied Currawong graph.doc
Description: MS-Word document
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