Thanks Philip. I am not a statistician and all I was doing was pointing out that the stats in a very general way seem to show a healthily increasing population of Crested Pigeons. As we all well
know, there are all sorts of issues with our stats such as the effect of the abundance of observers on the bird abundance statistics. They do seem, however, to be increasing or at least holding at healthy levels. Apart from wherever Charmian lives, lots of
people are telling the chatline that the CPs have not diminished in their area. I do not doubt that Charmian is right but I suspect that is just an annual aberration of some kind.
From: Philip Veerman <>
Date: Thursday, 7 December 2017 at 3:55 pm
To: chatline <>
Subject: RE: [canberrabirds] Crested pigeons
About “but was still 111% greater than the 30 year average” Yes that would be
right. However, bear in mind that the 30 year average includes many years that the species did not occur in Canberra at all. Even if the population evens off, which surely it must do, or even declines, surely over the years that 111% would tend to decrease
because we get into more than 30 years and thus more years that they are common, compared to the number of years in which they were not here at all. It was still a rarity until 1991 and numbers have increased since then. I don’t know anything of a recent
decline. I encounter them throughout.
Philip
From: John Harris [
Sent: Thursday, 7 December, 2017 3:35 PM
To: Charmian Lawson; COG
Subject: Re: [canberrabirds] Crested pigeons
They do not appear to have diminished in Gungahlin over the past 20 years. I don’t know where you live, but maybe it is just a chance variation this year. CBN this year said that the reporting rate was up, the abundance was slightly down
but was still 111% greater than the 30 year average. Others more knowledgeable may correct me but it is generally said the Crested Pigeons are extending their range in SE Australia. As a bird preferring open forest, reasonably thoughtful urban development
with street trees and green spaces does not necessarily reduce its numbers.
From: Charmian Lawson <>
Date: Thursday, 7 December 2017 at 3:16 pm
To: chatline <>
Subject: [canberrabirds] Crested pigeons
I have noticed that there are very few crested pigeons (or as we knew them as kids in Queensland, topknot pigeons) around in our area this year. Is this the case
in other parts of Canberra? Does anybody know why the population has diminished again?
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