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).
