Introduction to Chimney Swift Monitoring in London, Ontario

Adapted from the PDF prepared by Winifred Wake, Chimney Swift Liaison for Nature London, Feb 12, 2023

What are Chimney Swifts?

Chimney Swifts are small, black birds that are present in London from late April to early October. Often first detected by their twittering, swifts fly high above buildings and treetops, snatching insects from the air. Tiny twig-and-saliva nests are placed well down inside old chimneys, one nest per shaft. During spring and fall migration, groups of swirling swifts make spectacular dives into large diameter chimneys to spend the night. During the summer, non-breeding swifts roost together in old chimneys. Sometimes there is an active nest in a chimney at the same time.

Why Volunteer to Monitor Chimney Swifts?

  • Numbers in Canada have declined by >90% in the past 50 years.
  • The Chimney Swift was designated a Threatened species in 2009.
  • Monitoring
    • tracks which London chimneys swifts use and when.
    • provides data for calculating population changes.
    • offers insights into how well nesting attempts are faring.
  • Knowledge gained informs conservation action on behalf of swifts.
  • Monitoring is pleasant and relaxing, but can be exciting too.
  • Monitoring is a tangible way to help a species at risk.

What’s Involved in Monitoring Swifts in London?

  • Takes place May through September, mostly on Tuesdays.
  • Count or estimate swifts entering a chimney during 1 hour at dusk.
  • Field forms provided; enter data online.
  • Monitors work in pairs for safety, company, and mentoring.
  • Couples are welcomed.
  • Solos are paired with other solos.
  • Rotate among 14 chimney locations, possibly hosting a nest, a roost or both.
  • May choose a preferred area of London.
  • Monitor 1 to 3 times per month.
  • Schedule accommodates vacations and other absences.
  • Detailed monitoring guidelines and directions to chimneys.
  • Monitors receive feedback reports for each night.
  • Monitoring offers opportunities to make new friends, learn more about swifts, visit additional chimneys, participate in special events, and more.
  • All data are forwarded to provincial database at Birds Canada.

Nature London would love to have you join our team of friendly swift monitors! Friends and family are welcome too.

For more information or to sign up, contact

For a preview of the amazing sight of swifts entering a chimney to roost for the night, check this May 25/22 video link: