|Subject:||Quest for the breeding K Parrot|
|From:||"Philip Veerman" <>|
|Date:||Fri, 4 Feb 2011 17:20:47 +1100|
Martin has given us a good graph and some very good ideas. As I was the one doing the promotions for the GBS during those middle years I would support Martin's suggestion about the Leap Upward (LU1) in year 13 which may reflect the introduction of the DY category in that year and add that the Year 12 also sort of fits it in that the idea involved in the change was being promoted before the new design V3 of the GBS chart was issued. As The GBS Report explained Year 12 was in part transitional. So this is a likely factor but impossible to prove or separate out from other factors after the event. A look at other species will help. The issue has already been extensively addressed in Figure 22 a, b, c & d and adjoining text of The GBS Report, that looks at breeding data for all species combined over the years in an attempt to clarify major trends and biases in the data set.
I can't offer any ideas about years 14 to 16 for this species.
Martin made the assessment that The general shape of the chart remains the same if adjusted for number of sites operating in each year, so I decided to say with the simpler format. That is his choice and may be so but I believe it better to show relative to effort (number of charts). I would also suggest that in this case, the graph could show numbers of breeding records per year relative to number of records (not observations) of the species per year (i.e. the F value). Of course I could do that and provide a graph of that. Indeed I already have done that process for all species, as part of the analysis for doing the GBS Report. But I only have the first 21 years data.
-----Original Message-----Geoffrey's post raises a number of interesting thoughts.
From: martin butterfield [
Sent: Friday, 4 February 2011 3:38 PM
To: Geoffrey Dabb
Subject: Re: [canberrabirds] Quest for the breeding K Parrot
I have compiled a chart (see attached) showing the number of Garden Bird Survey observations of Dependent Young (DY) or - in the earlier years of the GBS - Fledgling (F) Australian King Parrots by GBS Year. (The general shape of the chart remains the same if adjusted for number of sites operating in each year, so i decided to say with the simpler format.)
My first thought is that if we ended up with no DY records for this species in the GBS it would be a cause for concern. To my mind that would indicate that wherever they breed -whether in the Brindies in Canberra Nature park, or in hollows in old street trees - the breeding season had been a major failure.
The graph shows a Leap Upward (LU1) in year 13 which may reflect the introduction of the DY category in that year. But if so, why did it drop(LD1) for the next three years before a major, and sustained Leap Upward (LU2) in Year 17? I can offer no hypothesis about the cause for LU2. The graph then shows a second Leap Downward (LD2) in year 22. This coincides with the loss due to bushfires - in December 2001 - of the pine forests alongside the Tuggeranong Parkway. Perhaps they formed a staging area for some of the birds moving down from the mountains? Perhaps the old remnant eucalypts in those forests were the site of the breeding hollows? The number of observations has - given operational constraints - stayed more or less constant since year 22.
I have tried to get a handle on how far the King-parrots (forgive me C&B) move. I have had little success with this. HANZAB indicates there have only 15 recoveries of banded birds in the period 1953 - 96 which is a rather small sample. However 73% of those recoveries were within 10kms of the original banding site, suggesting that the birds don't move far. As an example of distances that could be involved involved, according to GOOGLE Earth from the Cotter dam to the centre of Duffy is close to 9kms which would suggest that is close to normal operating range for the King-parrots in the banding studies. Perhaps he ACT bird are more adventurous or perhaps the sort distances travelled is an artefact of the research objectives of the banding studies.
As is often the case looking more closely would seem to raise more questions than it solves!
On Fri, Feb 4, 2011 at 1:07 PM, Geoffrey Dabb <> wrote:
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