Geoffrey
While I fully agree with your suggestion on the seasonal variation, it would go without saying that someone with a conservation bent would inquire whether the prevalence of the species is on the up or on the down.
My view is that with these two whistlers, they abundance is wobbling about over time, with no sharp long-term upward or downward trends, although the GBS is downish over the long haul. The data poses more questions than explanations, so it may be better to ignore it with some audiences.
Cheers
Paul
Paul Fennell
Editor Annual Bird Report
COG Databases Manager
026254 1804
0407105460
From: Geoffrey Dabb [
Sent: Thursday, 26 April 2012 9:15 AM
To:
Subject: FW: [canberrabirds] Whistler Reporting Rates
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.
Cheers
Paul
Paul Fennell
Editor Annual Bird Report
COG Databases Manager
026254 1804
0407105460
