Pembroke Chimney Swifts

Daryl Coulson dcoulson at
Tue Jul 30 18:19:59 EDT 2002

Hello Birders,

Last Wednesday, July 24th, I finally got around to searching for active
Chimney swift sites by driving around Pembroke after sundown and scanning
the sky and old chimneys. I had been admiring the swifts since their arrival
in the spring, frequently hearing their excited chatter and observing pairs
and small groups of as many as 16 birds throughout the summer. Recent
discussion on the Ontario breeding bird atlas listserve regarding chimney
swift observations moved me to action.

It did not take too long before finding the swifts congregating over the
west side of downtown Pembroke with the largest number of birds over the PMC
(Pembroke Memorial Centre - 393 Pembroke Street West, Pembroke). With each
passing minute the birds appeared to be tightening their flight circle and
forays while new arrivals came in from different directions until there was
a large gathering directly over the PMC building. I knew this was their
chimney when birds began dipping and diving towards the chimney mouth only
to swoop away again for another pass. This large swarm of swifts was in
circular motion counterclockwise which they maintained through the evening.
(Later watches showed that flock rotation to be clockwise on another
evening, and even clockwise switching to couterclockwise on another
The flight radius was about 200m+ when the birds began to organize and it
variably tightened to about 40m at the peak of activity after about 20
minutes. The flight circle plane was about 20m above the chimney entrance at
the peak of activity. Such a sight of birds in motion along with their
chorus of 'bubbly chattering' was awesome. A count or even an estimate of
the number of birds at this point was impossible since there were so many
birds in constant and variable motion and speeds. The excitement of the
birds was evident as they gathered and only with the passing of a gull
through their airspace was their organization briefly interrupted. Swifts
continued to swoop down toward the chimney mouth one after another only to
turn up at the last minute and rejoin the flight circle. It was as if no one
wanted to be the first to enter!
At 2103hr (about half an hour after sundown) the first bird entered with
following birds entering at random and irregular times until 2105hr when the
swifts began to literally stream into the chimney from the rotating flock.
Their entrance was amazing considering the approaching speed to the chimney
but the birds appeared to enter a controlled stall and dropped into the
chimney like a bat falling from the sky. The vast majority of birds entered
in the next 90 second period, with the last stragglers entering at 2108hr. A
count was made as birds entered the chimney, and it was found to be
difficult at times since the swifts were entering faster than one could
The total count on this first night, and considered a minimum number of
swifts, was 265 !  The next evening, Thursday 25th July, the same event and
routine was observed with a count of at least 246 birds. Then again on
Saturday night, July 27th, first birds entered a little earlier beginning at
2054hr and finishing at 2102hr, with at least 275 birds! It was on this
Saturday evening that I obtained some great video-recording of the event.

For those that have seen such an event you will understand and appreciate my
awe, and for those that have words can describe it!

Daryl Coulson
142 Mackay St
Pembroke, ON
dcoulson at

Directions: Pembroke is approximately a 1.5 hour drive up-river from Ottawa
on Hwy 417 which changes to Hwy 17. At Hwy 17 and 41 intersection turn right
if heading north onto Paul Martin Drive. Stay on this street through several
lights and turns until lights at Mackay Street. Turn left onto Mackay Street
and travel couple of blocks to Pembroke Street lights. Turn left onto
Pembroke Street West and travel through downtown to Pembroke Memorial Centre
(PMC) at 393 Pembroke Street West. Take first right at lights immediately
after PMC for parking at bottom of hill beside arena.

"Daryl Coulson" <dcoulson at>

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