Tweets

While I am cautious to present a second-hand report to the list, I wouldn't
do so unless I was sure of its accuracy. The following I hope you'll agree
is of interest.

Malcolm Bailey (a teacher colleague) is a keen, non-excitable observer of
the natural world and an occasional birding buddy of mine. Last evening
(Sept.8), he was in a boat on the Fraser River fishing for salmon (they
caught Sockeye, Pinks and Springs - but let's ignore this thread) on the
north side of Chilliwack Mtn. in the vicinity of Grassy Bar. This location
is approx 70 miles up the Fraser Valley from Vancouver.

As dusk was approaching, he became aware of a large number of swallows over
the river flying in many directions. As he looked, he noticed that the
birds were not only at low levels but at all levels in the sky including at
the limit of his vision as dots at high altitude. This stopped him fishing
and he observed the birds more closely. He was astounded by the number of
birds.

The birds descended and flew into an area approx. 100-150 yds x 50yds of 6'
to 8' high willows/alders on a sand bar (not connected to the shore) to
roost. He estimates that the number of swallows was at the absolute minimum
5000 and he believes that given the low light in which he was trying to
estimate, the number could have been double this.

The birds were all Barn Swallows (Hirundo rustica) and he accurately
described to me a mixed flock of adults and immatures and is sure the flock
contained no other swallow species.

He and his fishing partners all got streaked from the birds flying overhead.

Birds of B.C. vol. 3, Campbell et al, mentions flocks of up to 2000 birds
in southbound migration and also the mass roost phenomonen.

What intrigued me about Malcolm's observation was the number of birds and
their choice of what I assume is a relatively predator-free roost site.

Of course, then the questions come:

Is the Fraser Valley a major conduit of migrating Barn Swallows from the
interior of the province or is this an aggregation of local birds?

Are similar sightings made on the Columbia, Skagit?

Is this an unusual size flock or are similar numbers reported from other,
non-B.C., locations?

Are such migration roost sites regular from year to year or was this just a
fortuitous find for the birds?

Malcolm and I would welcome your thoughts, knowledge and ideas.

P.S.
We are going to try to access the site from land on Thursday to see if this
was a one day event or is happening more regularly during migration. I'll
let you know what we see.


* George Clulow *
* Langley School District *
* 4875 222nd Street Tel: (604) 530 2711(work) *
* Langley, B.C. Fax: (604) 530 2906 *
* V3A 3Z7 *