About recording Dependent young

To: "David Rosalky" <>, "canberrabirds" <>, <>, "Michael and Janette" <>
Subject: About recording Dependent young
From: "Philip Veerman" <>
Date: Mon, 7 Mar 2005 22:49:44 -0800
The issue about "dependent young" derives from an old discussion between Michael Lenz and I (and some others) about recording "dy" in the GBS, an issue that I had already covered in passing in my GBS Reports. We copied this correspondence to Martin who has made use of some of the ideas.
None of the GBS Chart instructions (for any Chart version - as listed in my GBS Report), mention that to record "DY", they needed to have been hatched within the geographic limits of the site. It is now clear that people have differed in their interpretation of the "dy" procedure. I believe that Michael believes that as "DY" is a subset of breeding records, the breeding also needed to have occurred within the geographic limits of the site. I had not thought of that as a necessity or that others would see it that way. I believe that if the DY were in the site, then that is enough to record them as such. The breeding graphs and the text in my 21 Year GBS Report makes it obvious that I used my interpretation, the complication is that not everyone did. The statistics in the "Birds of Canberra Gardens" also use the same interpretation, although of course the issue is not mentioned there.
Collecting data by week on "dy", regardless of knowledge of location of the actual breeding, (as I reckon often you don't know) means that we have some information (that we otherwise would not) about timing of and occurrence of breeding, which I see as useful. For example we have from "DY" data alone, lots of information about the timing and the steady increase in breeding of the King-Parrot over the 21 years of GBS data that have been consistently compiled and analysed. Even though the species has probably never actually bred within any GBS site. Michael expressed the (entirely defensible) view that on principle it really should only apply to dy that were born within the area. I think we have agreed to disagree on this. The issue is about location, more than functional description. It arises with things like cockatoos that typically move long distances after fledging. The young are still dependent but far from where they were hatched. Interpreting it as evidence that the birds bred nearby (or within the 100 metres for the GBS) is an entirely different (and difficult) question.
What do other bird surveys do?
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