Red-rumped Parrot abundance

[Duncan McCaskill <>]

For Red-rumped Parrot, the reporting rate and the abundance measure closely track each other. The abundance measure looks noisier - for example in 2004/05 there were a few records of large flocks at one site, giving a large peak in the graph below.  The average group size has hovered around 5 for most of the survey, with lows around 3.5 in the mid 90s, highs around 5.8 in 1984/85 and 30 years later in 2015/16. The peak of 9.4 in 2004/05 is probably an outlier.

​ Duncan.

On 6 June 2017 at 22:34, Philip Veerman <> wrote:

Actually the abundance statistic from the GBS is the “A” value, the one that has traditionally been used for the GBS graphs in the COG ABR and used in The GBS Reports and BOCG. The R value is, as Duncan indicates, merely the Reporting rate, and has rarely been given prominence in COG information. It is the proportion (in this case %) of observer weeks, at which the species was recorded. This is not abundance, it in no way uses the available information as to the numbers of birds observed. Although there is an obscure connection between the two statistics. If group size was always a constant (such as always one, which it clearly isn’t), then there is a direct connection. The GBS Report explores this connection, as a highlight of the GBS.

 

Philip

 

From: Duncan McCaskill [mailto:m("gmail.com","duncan.mccaskill");" target="_blank">duncan.mccaskill@gmail.com]
Sent: Tuesday, 6 June, 2017 7:52 PM
To: calyptorhynchus .
Cc: Canberra Birds
Subject: Re: [canberrabirds] Red-rumped Parrot abundance

 

Summaries of COG's data for each species are available on the COG website under Our Birds / Bird Info. The Red-rumped Parrot summary sheet is here: http://canberrabirds.org.au/wp-content/uploads/2015/02/Red-rumped-Parrot.pdf (PDF download).

 

This graph of the reporting rate from COG's Garden Bird Survey shows a decline to about 2002, followed by an increase back to 1980s levels. 

 

 

Duncan McCaskill

Coordinator, Garden Bird Survey.
​

 

On 6 June 2017 at 17:16, calyptorhynchus . <> wrote:

Do the COG databases and other collections support my idea that RRPs have become more common over the past 20 years in Canberra?

--

John Leonard