Yellow-tailed Black-Cockatoos (YTBC)

[martin butterfield <>]

Yesterday (11/2) Nick Payne posted a message about YTBCs which included:

"I've certainly noticed a lot more YTBCs in the suburbs over the past week or two than I would normally expect. ...and when I was cycling home on Monday there was a flock of about two dozen in Curtin near the intersection of Cotter Rd and McCulloch St.  I wondered at the time I saw the two dozen whether they had come into the suburbs because of smoke from bushfires."

It is of course too early to tell whether the bush fires in Victoria have had any effect on YTBCs moving into Canberra.  However, the two graphs attached, showing GBS data, may be of interest in showing the impact of the 2003 ACT (and nearby NSW) fires on the species.

The first shows the values of A by month for the first 22 years of the GBS and the last three years (25 - 27).  I omitted years 23 and 24 as there was a massive movement of the birds out of the mountains in those two years, which has 'calmed down since then.  This graph suggests that there has been a noticeable change in the birds behaviour since the fires.  The second graph shows that the three years are similar in terms of the number of birds reported (observer effort between the three years is not so dissimilar as to distort the broad thrust).  The very high peak in April of year 27 reflects a flock of up to 110 birds turning up at a site in Wamboin.

Thus I'd suggest that Nick's observation of a change is an example of the (new) seasonal movement of birds into the ACT.  I will try to remember to check what is revealed by Year 28 data in 12 months time!

Martin

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