Pied Currawongs

A recent post to the Mallacoota Community News Facebook Group a post commenced

"Keep an eye out for birds and weather . Remember “When the currawongs come down from the mountains, it’s a sign.....”"

This rang a bell with me about my early days in Canberra.  At that time (roughly the 1980s) the Pied Currawongs would come down from the Brindabellas each Autumn and then in Spring return to the
mountains to breed.  In more recent times this pattern has changed with the birds staying in the urban area longer.  This is thought to result from them finding that human environments have easily accessible food resources (dog food etc) that make life easier for them than gathering traditional food in the mountains.

This is illustrated in the following chart, from the Canberra Ornithologists Group Garden Bird Survey, where the series years less than 10 is 1983-1992.
The difference between the two series seems very clear.

For Mallacoota I have taken data from eBird of the number of lists reporting Pied Currawong and the number of Currawongs reported. The number of lists submitted fidders greatly from month to month. ranging from 324 in January to 42 in July.  (Which says something about the importance of tourists to the area, but that's another story.)  So I have divided the number of Currawong lists and the number of Currawongs by the total number of lists to get some rates as shown in the next chart.

 The lines are quite variable, possibly reflecting which sites are being reported.  So to remove that "noise" from the lines I have calculated (or rather, Excel has calculated) a polynomial trend line for each series.  That shows  rather nice - approaching significant trend - peak in June of the number of Currawong included.  The curve for number of lists reporting Currawongs is not significant different to a flat line.hovering around 1 chart in 3 (a rate of 0.3).

As there aren't a HUGE number of lists for Mallacoota I decided to repeat the exercise for the whole of East Gippsland.

That shows a more marked movement to a peak in March which is more or less sustained until Spring.