In view of the information provided by Paul for more recent years, I shall, with Philip’s permission, choose a slide showing seasonal variation rather than trends over the years. This has a secure observational basis, and will probably be of more interest to the audience in any event.
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.
Editor Annual Bird Report
COG Databases Manager