Monarch Watch is participating in the Project Monarch Collaboration to deploy BlūMorpho radio tags on monarchs during the fall migration. The Project Monarch Collaboration was founded through a partnership between the Cape May Point Arts & Science Center (CMPASC) and Cellular Tracking Technologies (CTT) and involves lots of conservation organizations and scientists and an amazing group effort. BlūMorpho tags are extremely lightweight, solar-powered radio tracking tags that can be attached to the thorax of monarchs.

The race is on!

As part of this project, more than 600 BlūMorpho solar-powered radio transmitters have been deployed this migration season, including more than 500 during the fall 2025 migration and another 150+ ahead of the spring 2026 migration. Monarch Watch Director Kristen Baum has been providing many updates on the movement of these monarchs and they are all available on our 2025–2026 season updates page.

For more information about the effort by our Mexican colleagues, you can check out this news story about the tagging effort at El Rosario.

Press release: Tagged Monarchs Surge Across the US Border, Reaching Arkansas, Louisiana, and Texas as Scientists Watch a Historic Spring Migration Unfold in Real Time

INTRODUCTION TO RADIO TAGGING

BlūMorpho solar-powered radio transmitters (also referred to as “tags”) provide an amazing opportunity to track the paths of individual monarch butterflies. Each tag is ultralight, weighing less than a grain of rice, and are carefully attached to a monarch’s thorax. Once deployed on a monarch, the tag uses Bluetooth crowd-sourced location networks to increase the number of detections.

To learn more about how this project began and how BlūMorpho tags work, visit the CTT/CMPASC Project Monarch Collaboration website.

This groundbreaking project paves the way for new opportunities to study the monarch migration. Notably, these updates show more precise locations in near-real time during a monarch butterfly’s journey, both during the fall migration as well as northbound movement in spring.

MONARCH WATCH INVOLVEMENT

In September 2025, Monarch Watch deployed 30 BlūMorpho tags on migratory monarch butterflies. Based on the preliminary results from this year and the expected mortality during the migration, the success of these radio tags is very good.

Of the 30 monarchs that we tagged, 33% (10) have been detected in Mexico, 63% (19) in Texas, and 70% (21) in Oklahoma. Monarch MW001 reached the Monarch Butterfly Biosphere Reserve first on November 6, 2025. Since then, a total of 6 of our radio-tagged monarchs have been detected within the overwintering sanctuaries. We were particularly excited in early January when MW005 was detected at Cerro Pelón. Prior to that, MW005 was last detected on October 31 near Matagorda Island, which is northeast of Corpus Christi, Texas.

We've previously documented our involvement in the project through several blog posts:

Feb. 23, 2026 – Monarchs on the Move!
Feb. 16, 2026 – Get Ready to Follow the Spring Migration in Real Time
Nov. 17, 2025 – Tracking Individual Monarchs with Radio Tags as Part of the Project Monarch Collaboration
Nov. 7, 2025 – Radio-tagged monarch MW001 arrives at the MBBR

Previous estimates (see Monarch Population Dynamics: Issues of scale) have suggested that 20% (or 1 out of 5) or fewer of monarchs that start the migration across the breeding range make it to the overwintering sanctuaries in central Mexico. While we don’t know the origins of the wild-caught monarchs that we tagged with BlūMorpho tags in Kansas, we do know that they had many fewer miles left to fly (1370 miles) by the time we tagged them than those tagged by many of our colleagues and collaborators on this project. For example, those tagged in Long Point, Ontario, had to fly at least 1960 miles to reach the overwintering sanctuaries, while those tagged in Harrisonburg, Virginia, flew at least 1830 miles.

PROJECT MONARCH MOBILE APPLICATION

You can download the free Project Monarch Science app via your device’s app store and from there, you can see a host of information about many of the radio-tagged monarchs.

The app is divided into two main sections: Detect and Data. Under each of these sections, you can find additional information:

Under DETECT, you can use your device to start and stop scans for tagged monarchs in your area. Any detected tagged monarchs during a scan will be displayed via a list on your screen. For any tagged monarchs that are listed on your device, you can then upload those detections to the Project Monarch database.

Under DATA, you’ll find lists of individual monarch butterflies (butterfly icon), a map of the latest locations of all tagged monarchs (map icon), and leaderboards featuring highest number of individual monarchs detected (trophy icon) and highest total detection count (people icon).

Under the monarch icon, search for specific tagged monarchs (such as Monarch Watch’s, all labeled with “MW”) and click on one to view individual stats, including a monarch’s sex, when it was released, date of last detection, and distance from release. You can also toggle to a map view to see its last detected location.

Under the map icon, make sure to zoom in as far as you can so you don’t miss any monarchs on the map.

PROJECT MONARCH COLLABORATION

More than 25 research organizations make up the Project Monarch Collaboration. We’re excited that we could participate in what’s been an amazing contribution to science – and also a lot of fun! We’ve enjoyed sharing ideas, information, questions, answers, and other experiences with so many dedicated scientists.

Logos of Project Monarch Partners.

PROJECT UPDATES

As mentioned above, Monarch Watch Director Kristen Baum has been providing many updates on the movement of these monarchs and they are all available on our 2025–2026 season updates page. Thank you for your interest!