International Monarch Monitoring Blitz
The International Monarch Monitoring Blitz invites community scientists from across North America to come together with the shared goal of helping to protect and conserve the beloved and emblematic monarch butterfly. Data collected by volunteers each year support trinational efforts to better understand the monarch butterfly’s breeding productivity, range, and timing in North America.
This year’s Blitz took place between 29 July and 7 August. You can learn more about the results of this trinational effort, here.

Why Community Science?
The information collected by North American community science observers helps researchers identify priority areas for monarch conservation actions. Thanks to this engaged community of observers, monarch researchers will soon be able to analyze trends in summer breeding population sizes. All partner organizations have agreed to share volunteer-collected data to a central data repository. In this way, anyone can consult and download Blitz data by visiting the TRINATIONAL MONARCH KNOWLEDGE NETWORK.


Volunteer participation and the engagement of volunteers grows year after year, and experts believe that the Monarch Blitz database, made up almost exclusively of observations shared by volunteer community scientists, will achieve the original objective set for the Monarch Blitz by the Trinational Monarch Conservation Science Partnership: a rigorous estimation of the size of the summer breeding population, similar to what is done with the overwintering populations in central Mexico and coastal California.
Furthermore, researchers are interested in assessing population trends. Reporting the number of caterpillars and the number of milkweed stems can allow the calculation of a caterpillar-to-milkweed ratio. Researchers can then use this ratio to estimate the size of the population of monarchs that are migrating to Mexico at this time of year.
Which Community Science Program is Right for You?
Participating in the Monarch Blitz requires you to simply track your observations of the monarch butterfly. If you spot a monarch egg, caterpillar, and/or adult or milkweed, no matter where you are near the end of July or beginning of August, you’re encouraged to share your observation with one of several Community Science programs displayed below.
Curious which program is right for you?
Have a look through the programs below to find one that works for you!
Contact
Georgina O’Farrill
Head of Unit, Outreach and Partnerships
(514) 350-4336