International Monarch Monitoring Blitz
Every Observation Matters!
The International Monarch Monitoring Blitz is back for its 10th anniversary! From 31 July to 9 August 2026, join the celebration and help search for monarch butterflies and milkweed plants in your area.
The Monarch Blitz is a community science initiative open to anyone in North America. Last year, over 9,000 volunteers contributed thousands of observations.
For our 10th anniversary, help us reach our goal of 10 Years: 10,000 More Participants!
How to Participate
Participation in the Monarch Blitz is easy, and anyone can take part, whether in an urban or rural setting!
Choose the Community Science Program that’s right for you, based on where you live
Familiarize yourself with how the program’s platform works (some platforms may require creating an account, but they are all very easy to use and take just a few clicks to get started)
During the Monarch Blitz, go outside and look for milkweed, the monarch’s preferred host plant
Inspect the plants for monarch eggs, caterpillars and chrysalises and look out for monarch butterflies
Report your observations and the number of milkweed plants you saw
Whether you participate once or throughout the 10 days, every observation matters and helps scientists better understand how to conserve this iconic species!
Highlights from the 2025 International Monarch Monitoring Blitz:
We are celebrating nine years of Community Science with very encouraging results from this year’s Monarch Blitz. This year’s results surpassed previous participation rates! Here are some highlights from the 2025 trinational effort:
- 19,705 observations
- 9,611 participants
- 33,882 monarchs observed
- 71,203 examined milkweeds
See our full statement, and learn how you can download Blitz Data, here.
Summary of the last nine editions (2017-2025) of the International Monarch Monitoring Blitz, a community science initiative:
- 24,531 participants across Canada, Mexico and the United States
- 51,557 observations
- 461,916 milkweed plants monitored
- 162,870 monarchs observed
- 56,558 eggs
- 50,199 caterpillars
- 2,868 chrysalises
Facts about the Monarch
- Monarch butterflies weigh less than a gram.
- There are two recognized migratory routes in North America: Eastern and Western.
- Migration covers 3,000-5,000 km (2,000 to 3,000 miles) and spans three countries.
- The Eastern migratory population has declined by more than 80% in 20 years.
- The Western population has declined by 99% since the 1980s.
- Everyone can help the monarch butterfly by participating in community science, creating monarch-friendly habitats, and spreading the word about the monarchs’ status and importance as a pollinator.
Image courtesy of Amy Evoniuk Photography.
Participation
The 2025 International Monarch Monitoring Blitz was a great example of community science participation and collaboration across North America. The results have also been showcased through the CEC’s MapMonday initiative which highlights North American geospatial data, especially in relation to the CEC’s North American Environmental Atlas.
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.
Choose a Community Science Program
Mission Monarch
Mission Monarch is a community science program that gathers data on monarch and milkweed distribution and abundance. The data collected helps researchers identify monarch butterflies breeding hotspots and implement efficient conservation actions. Participants find milkweed, look for monarch caterpillars and share their observations of milkweed, monarchs, eggs, caterpillars and chrysalis with scientists on the Mission Monarch website.
The program is a joint initiative of the Insectarium de Montréal | Espace pour la vie and the Institut de recherche en biologie végétale. It is part of an international research and education effort aimed at saving the migratory populations of this endangered species.
iNaturalistMX
iNaturalistMX is a social network for community scientists where you can learn about Mexico’s plants, mushrooms and animals and help advance scientific knowledge about nature. iNaturalistMX is an encyclopedia, photographic catalog, map library, field guide and especially an educational hobby. You can use its app to record your nature observations in image or audio form and share them with the iNaturalistMX community, which will help you identify the species. The app activates your GPS to automatically record the date and location of your photos and allows you to navigate a map of observations recorded both near you and in other locations.
In addition, within the iNaturalistMX community, specific projects are developed to integrate information on species or ecosystems. In Mexico, the Monarch butterfly in Mexico project integrates all information on monarch monitoring. This project enhances knowledge about monarchs in Mexico and strengthens decision-making in the country’s Protected Natural Areas and elsewhere by identifying the principal sites in terms of conserving and protecting monarch migration in Mexico.
iNaturalist
The Western Monarch Milkweed Mapper is a community science effort to map monarch butterflies and milkweed across the Western United States. To preserve and protect populations in western states, we need to better understand where and when monarchs and their milkweed host plants can be found. Data compiled through this project will improve our understanding of the distribution and phenology of monarchs and milkweeds, identify important breeding areas, and help inform monarch conservation needs.
Your help is critical to the success of this project! You can participate in this effort by uploading your photos of monarch butterflies (all life stages) and milkweed to the iNaturalist Project. Have fun while learning more about monarchs and the special habitats they depend on in your area!
The Western Monarch Milkweed Mapper is a collaborative partnership between The Xerces Society, Idaho Department of Fish and Game, Washington Department of Fish and Wildlife, National Fish and Wildlife Foundation and the U.S. Fish and Wildlife Service.
Journey North
Join the Journey North Monarch & Milkweed Project to track key phenological events in the life cycle of monarch butterflies and milkweed. An easy-to-use data entry portal allows you to quickly submit your observations.
In the spring, track first arrivals of migratory monarchs and first emergence of milkweed. During summer, document monarch breeding and feeding activity and the presence of milkweed. And in the fall, report monarch roost sites and peak migration events as monarch butterflies travel to overwintering sites.
Watch the migration unfold through real-time maps and subscribe to receive weekly news updates. Beyond monarchs and milkweed, you can help Journey North track the migration of hummingbirds, orioles, loons, swallows and many more species.
Correo Real
Correo Real is a program of Profauna, the Mexican Wildlife Protection Society, which helps protect and preserve monarch butterfly migration in Mexico through education and community science activities, conservation actions and partnerships with the local communities, civil society organizations, the public sector and private enterprise.
Correo Real’s story began in 1992 with an initiative to form a network of concerned volunteers dedicated to studying and safeguarding this incredible natural phenomenon, as well as recording and sharing information on the monarch’s migratory routes in Mexico. This innovative approach has since inspired other environmental education and community science programs.
iNaturalist Canada
Part of the global iNaturalist network, iNaturalist Canada combines one of the world’s most popular nature apps with a bilingual interface, helping you instantly identify plants and animals anywhere you go; from backyards and neighborhoods to remote forests and countrysides.
Connected with a community of over a million scientists and naturalists who can help you learn more about nature! By recording and sharing your observations, you’ll contribute research quality data for scientists working to better understand and protect nature. It’s community science that is fun, educational and impactful.
The Canadian Wildlife Federation is a national, not-for-profit charitable organization dedicated to conserving Canada’s wildlife and habitats for the use and enjoyment of all. By spreading knowledge of human impacts on wildlife and the environment, carrying out actions to conserve and restore species and habitats, developing and delivering conservation education programs, recommending changes to policy and programs and co-operating with like-minded partners, CWF encourages a future in which Canadians can live in harmony with nature. For more information, visit CanadianWildlifeFederation.ca.
Why Participating in the Monarch Blitz Matters
The International Monarch Monitoring Blitz is a call to action for individuals, organizations and community scientists across North America to join efforts to conserve monarch butterflies and the habitat they depend upon. For ten days each summer, everyone is encouraged to step outside, search for monarchs (eggs, caterpillars, chrysalises or adults) and milkweed plants, and share their observations on one of several data platforms. Scientists use these observations to better understand how to conserve monarch butterfly populations.
The Monarch Blitz is a unique cross-border effort to conserve one of North America’s most iconic migratory species: the monarch butterfly. Because monarchs migrate across the continent, cross boundary collaboration is essential to better understand the species, its movement patterns and the habitats it depends on. Understanding and conserving them requires collaboration that goes beyond borders.
Monarch butterfly populations have experienced a significant decline over the last few decades. While the 2024-2025 wintering season saw an increase from the previous year, this remains one of the lowest recorded population sizes and highlights the ongoing challenges for monarch conservation, as well as the urgent need for coordinated, evidence-based conservation efforts.
The monarch butterfly is a keystone species, not only in the habitats where it breeds but also in those through which it migrates. By maintaining healthy monarch populations and conserving their habitats, particularly milkweed and nectar-rich areas, we are simultaneously protecting the broader environment that sustains many other species as well. Monarch butterfly conservation efforts, therefore, play a vital role in safeguarding biodiversity across North America, offering a powerful opportunity to support entire ecosystems through the protection of a single, iconic, North American species.
Learn more about monarchs, their life cycle, and why they need our help.
- Monarch butterflies weigh less than a gram.
- The monarch’s wingspan ranges from 8.9 to 10.2 centimeters (3.5–4.0 in).
- There are two recognized migratory routes in North America: Eastern and Western.
- Migration covers 3,000-5,000 km (2,000 to 3,000 miles) and spans three countries.
- The Eastern migratory population has declined by more than 80% in 20 years.
- Everyone can help the monarch butterfly by participating in community science, creating monarch-friendly habitats and spreading the word about the monarchs’ status and importance as a pollinator.
The Monarch Blitz database is made up almost entirely of observations shared by volunteers. Since monarch butterflies and milkweed populations cover such an extensive portion of North America, the participation of volunteer community scientists is key for furthering our understanding of these species. In the context of climate change, the range of monarchs and milkweed is likely to be impacted, highlighting the need for gathering and analyzing robust, long-term data in order to better understand population and habitat trends.
The information collected by the yearly growing number of participants across North American helps researchers identify priority areas for monarch conservation actions. Thanks to everyone sharing their observations during the Monarch Blitz, researchers can study the observation data and analyze trends in summer breeding populations.
The Monarch Blitz data help provide an estimate of the size of the summer breeding population. 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 will be traveling to the overwintering grounds in Mexico.
All partner organizations have agreed to share volunteer-collected data to a central data repository. In this way, anyone can consult and download Monarch Blitz data by visiting the data by visiting the Trinational Monarch Knowledge Network.
Celebrating Community Science Efforts
We were surveying for butterflies at Panola Mountain State Park.
We monitored milkweed at 5 properties that are managed by Wissahickon Trails
Partners
The Monarch Blitz is organized by a collaboration of organizations across North America, including: the Commission for Environmental Cooperation (CEC), the Insectarium de Montréal | Espace pour la vie, Environment and Climate Change Canada (ECCC), the Canadian Wildlife Federation (CWF), the Monarch Joint Venture, Journey North, the U.S. Fish and Wildlife Service (USFWS), the Xerces Society for Invertebrate Conservation, Profauna A.C. and Mexico’s National Commission of Protected Natural Areas (CONANP).
Contact
Georgina O’Farrill
Head, Communications, Outreach and Engagement
(514) 350-4336