FW: [canberrabirds] Whistler Reporting Rates

To: <>
Subject: FW: [canberrabirds] Whistler Reporting Rates
From: "Geoffrey Dabb" <>
Date: Wed, 25 Apr 2012 13:44:05 +1000

Thank you for taking the trouble to do this Paul.  Very interesting.  With no expertise, least of all in mathematics, I am not deterred from offering the following comments.


First, your graph on the GBS reporting rate broadly mirrors Philip’s based on abundance – for the comparable period.  Philip goes back 10 years earlier, but stops at mid-2002.  Your graph for the more recent years might well indicate a reduction in GW numbers in gardens due to the fires (January 2003).  I note from the ABRs that GBS numbers for the GW were –


2001-2002: sites 69.5%, weeks 45

2002-2003: sites 72.4%, weeks 38

2003-2004: sites 73.3%, weeks 52 (post-fires dispersal?)

2005-2006: sites 52.9%, weeks 43

2009-2010: sites 54.55%, weeks 37


Not all that dramatic, but a variable not brought out in that table would be the number of sites reporting presence in the same week, which should be reflected in your reporting rate – and in the abundance figure, since most observations are of a single bird. So one theory would be that since the fires (2003-present) there has been a decline in garden GW numbers that parallels the earlier decline (1987-2001)  in (for whatever reason) RW numbers.  I would be interested in the 2011 figures – and in those for the current year which I feel might well show an upswing if other gardens are like mine.


As to the other surveys, these show, I would say, the RW going along at a 5-10% reporting rate and the GW at a 15-20% rate – both pretty steadily and no doubt with their respective seasonal (and habitat preference) variations.  It does raise a question why the GW should have declined in gardens but not in woodlands ….  



From: Paul Fennell [
Sent: Wednesday, 25 April 2012 12:09 PM
To: 'canberrabirds chatline'
Subject: [canberrabirds] Whistler Reporting Rates


Hello everyone, including whistlers, tweeters, and chirpers!


I have constructed two graphs, one from the GBS data, and one from all non-GBS surveys, showing the reporting rates of both Golden and Rufous Whistlers.


I calculated the reporting rates by:

For the GBS survey, counting the number of weeks the species was recorded each year, divided by the total number of weeks recorded that year, to arrive at a percentage.

For the other surveys, counting the number of data sheets recording the species each year, divided by the total number of sheets recorded that year, to arrive at a percentage.






The two graphs show some interesting ups and downs, including one would suspect, the effect of the bushfires on Rufous Whistlers.  I leave it to you to make further interpretations.






Paul Fennell

Editor Annual Bird Report

COG Databases Manager


026254 1804



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