Monday, 24 September 2012

Chimney Swift Roost
Dickson Street Public School
Cambridge, ON

    For the past two years Bill Read, Jerry Guenther and I, and several other dedicated volunteers, have monitored the Chimney Swift Chaetura pelagica roost at the above location. This school is a marvelous old heritage building (built in 1888), still in use as a school today. From what we have been led to believe it will continue to be used as a school for one more year, following which it is scheduled to be developed as condominiums. It is our fervent wish that whatever the plans for the building, provision is made to leave the chimney intact.
    Apart from sporadic visits during the day we have only monitored the chimney at dusk. We have a pretty good record now of the numbers of birds that use the chimney as a roost but little information as to whether any pairs have used the structure as a nest site. It seems likely that this would be so.
    For anyone craning their necks skywards the signature flight of mated pairs of this aerial species is easy to detect. The birds will snap their wings into a distinctive "V"and fly closely together one behind the other.
    As dusk approaches the sky which only moments before contained but a few birds is suddenly a whirling, cavorting, chattering mass of birds showing the most incredible flying skills one could ever imagine. It is truly an event worth making an effort to see. It is in my opinion one of the great spectacles that nature provides. The birds swoop tantalizingly close to the chimney and seem to make a feint at going in but bank sharply and rejoin the maelstrom. Then, on some cue perhaps, unknown to us, a few birds start to enter the chimney, plunging in at breakneck speed. We struggle frantically to maintain the semblance of an accurate count as more and more individuals enter in ever greater groups. Within five to ten minutes it is all over and the skies are empty of swifts.
    Chimney Swift roosts may contain as few as twenty or thirty birds or as many as several thousand. Our maximum count this season was a little below five hundred, fully recognizing that there is a margin of error in the count. Given the fact that, for the most part, the same people do the count in the same way we believe that the margin of error is basically the same from night to night, so the figures stand up to scrutiny.
    We would encourage anyone interested to join us next August when swifts seem to come from other locations to use this roost. It will provide great entertainment and not a little insight into the natural world. 




    My wife is the photographer in the family and she struggled mightily to get a few decent pictures but without success. The pictures shown here were taken by David Beadle ( http://www.flickr.com/photos/10821818@N07/5784283872/in/set-72157626803952828 ) and he has kindly given us permission to use them. They are remarkable studies of a species notoriously difficult to photograph. We owe David a great vote of thanks.



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