30 years of Bluebird Monitoring of the Carol Porter Mountain Bluebird Trail at Cypress Hills
In the last 30 years of monitoring of the Carol Porter Trail there have been three seasons with low numbers of bluebirds fledged: 2002, 2009, and 2021. The weather appears to be the main factor in the number of bluebirds fledged.
In 2002 there was a snowstorm on 22-23 May with 23 cm of snow and temperatures between - 8 and +7 degrees.
In 2009 there was a snowstorm on June 5 to 7 with temperatures ranging between 0 and 12 degrees. On June 5 there was 9 cm of snow & a gusty NE wind, on 6 there was 5 cm of snow & a gusty NE wind, and on June 7 there was 2 cm snow on the ground.
This past nesting season (2021) had a snowstorm on May 20 to 23 with temperatures between -2 and +9, with 7 cm of snow on the ground. A little over a month later the maximum daytime temperature was between 37 and 40 degrees from June 29 to July 2.
In 2002 and 2009 the snowstorm decimated the first brood with 240 sterile eggs in 2002 and 125 abandoned eggs in 2009. In 2021 46% of the first brood eggs were sterile. In 2002 and 2009 the number fledged in the second brood exceeded the first brood, that was not the case in 2021 where the second brood fledged was less than the first brood fledged.
Bluebird nesting information from: