Re: Swifts in Carwoola

[martin butterfield <>]

No. no Geoffrey despite the temptation evident in your suggestion I would never call you a cynic. A sceptic .... perhaps.

What the information suggests to me is that the situation is as shown in the attached. graphic (gmail doesn't allow me to embed pix in the guts of the message)  I think the number of obs of 1 or 2 birds suggests people generally refrain from expanding the boundaries to those shown by the weak line to include the whole flock but try to reflect the fact that a single bird from the flock has snuck in to the boundary of the site.

C'est le plus meilleur du toutes les mondes possibles

Candide

On Sat, Mar 20, 2010 at 12:02 PM, Geoffrey Dabb <> wrote:

Call me a cynic, Martin, but re our previous discussion I think the ‘elastic site’ effect might also be at work:

 

 

From: martin butterfield [
Sent: Friday, 19 March 2010 9:32 PM
To: COG List
Subject: [canberrabirds] Re: Swifts in Carwoola

 

Following my report earlier this evening an observer commented that they had seen a single swift over their yard.  After a good description of swift jizz they concluded "... do they fly solo or would this one have been a stray from a nearby out-of-sight flock passing by? I thought they flocked!"

The attached document shows the distribution of "flocks" of swifts reported in 28 years of GBS.  Clearly reports of 1 or 2 swifts are not uncommon.  There are enough references in HANZAB to 'single birds' to suggest that some birds may be 'loners' but possibly this simply reflects that relatively dispersed food resources lead the more typical large flock to be dispersed when passing over a small area such as a GBS site..

At a more detailed level - and possibly of interest in view of recent posts about counting flocks - once a flock is greater than 5, there is a distinct digital preference for numbers ending in zero.  Given the speed at which these birds travel it is not surprising that observers round them to the nearest 10.

Martin

On Fri, Mar 19, 2010 at 6:40 PM, martin butterfield <> wrote:

Some smoke is being blown up from the SE - presumably from one of the many hazard reduction burns listed on the RFS web site.  Some woodswallows and the occasional Swift were cruising through this, as reported by a resident on the Widgiewa Rd ridge.  They were unobliging in visiting my GBS site (about 1km NE).

 

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