Paucity of Crested Pigeons? - GBS Data from continuous sites

["Philip Veerman" <>]

I agree with both that it looks genuine, as in widespread. What does the graph show in respect of the G values over the years?

 

I would be surprised if Spotted Doves has anything to do with it at this stage, as they are still comparatively rare here and they don't compete for nest sites. Maybe food competition from parrots is a factor. Though I still go with that it is normal for a species to decline a bit after having gone through a huge increase in population. No huge rate of increase of anything is ever sustainable indefinitely.

 

Philip

 

-----Original Message-----
From: martin butterfield [
Sent: Tuesday, 28 May 2013 8:34 AM
To: Duncan McCaskill
Cc: canberra birds
Subject: Re: [canberrabirds] Paucity of Crested Pigeons? - GBS Data from continuous sites

Duncan 

I agree that it looks like a genuine drop, and from your graph yesterday, a widespread one.  

Hopefully some of the biologists in this group will be able to suggest reasons for this.  The kite I would fly is to note that one of the problems with Spotted Doves invading Alice Springs was their competition with the native pigeon species.

Martin

On 27 May 2013 22:42, Duncan McCaskill <> wrote:

Here is another chart showing the Crested Pigeon "A" value from 2003 to 2012.

The red line for the whole GBS. The blue line is restricted to sites that were operating all 5 years before 2012 (from 2008). That is 49 sites from 2008 onwards, but dropping down to only 25 sites for 2003. It looks to me a lot like a real decline.

 

Duncan McCaskill

GBS Coordinator.

On 27 May 2013 17:25, John Layton <> wrote:

As I watched a group of Eastern Rosellas feeding among oak mast not far from home during the weekend, they were joined by a lone Crested Pigeon. It struck me that I’ve seen very few Crested Pigeons in the vicinity for several months. Certainly none of the large 30 to 40-bird flocks that were prevalent round here previously, and very few smaller groups/flocks. Perhaps this may be because they’ve spread further afield due to greener pickings since the drought.  Has anyone noticed a similar reduction in their numbers?

 

John K. Layton

Holt.

--
Martin Butterfield

http://franmart.blogspot.com.au/