Last night, I was reminded by son Ryan, of that which I know and should have remembered (the Einstein moment). Successful breeders in the southern-most portions of the swifts distribution e.g., Texas, can produce two clutches per year. In Manitoba, however, the birds simply run out of time to produce a second clutch before migration. BUT, if the first nesting attempt failed and a second nest was started, that might explain the ongoing confusion and feeding behaviour seen at this late date. The down-the-chimney details for the SE Club Amical will never be known – there is no accessible cleanout trap and we have no nest cam. The best strategy to decode the mystery is to continue watching for evidence of fledging and start polishing up the rear view mirror.
Waiting for late-fledging swifts is happening beyond St Adolphe. There are at least two other nest sites which could produce fledglings in the next week or so. A multi-site blitz took place in Portage on August 17. The monitoring team – Gord, Janice, Joyce, Jim, and Cal – reported intense feeding activity at the Victoria School/Red River College site. There were 7 feeding cycles before the roosting hour and a total of 5 adults roosted. That means up to 3 helpers were on site or a pre-migratory group assembled at the nest site; this activity also was noted during monitoring on August 8 and 10.
On August 18, late nesting Chimney Swifts were discovered by a Winnipeg chimney sweep at St Avila School – see our August 21 blog “Peering Down the Chimney“. Jeff saw 3 juveniles in the nest which means that they were < 21 days old. Fledging takes place at 28-30 days of age = after August 25 at the St Avila site. That would be a new record for the latest date of fledging in Manitoba.
To put “late-fledging” in perspective, migration is underway. Ken reported that the Dauphin roost emptied between August 6-10. David and Adolf recorded 0 swifts at the Assiniboine School roost on August 6. Two unsuccessful nest sites in St Adolphe were unoccupied on August 17 (Jacquie at Brodeur Bros.; Rob at NE Club Amical) while 2 other successful sites had lower counts indicating a redistribution of family groups (Frank and Lewis at the Church: fledged young July 30 – 8 roosted August 5 – 3 roosted before the roosting hour August 17); Barb at Main St.: fledged August 12 – 2 juvenile entries August 17).
While we continue to monitor the progress at the remaining active nest sites, your patience is appreciated too. The final August monitoring update is still a work in progress…