The information in this state update was provided by Maggie Hirschauer at  Please contact her for additional information about the update.


by Beth Waterbury


We monarch enthusiasts from the Big Sky State are very excited to join Western Monarch Advocates’ growing interstate network! Thank you for welcoming us. Montana is a bit of an outlier among the western monarch states, sitting at the far northern tier of North American monarch range and split by the Continental Divide into distinct western and eastern regions. Yet Montana supports pockets of high-quality milkweed habitats and breeding populations of monarchs on both sides of the Divide—even in 2020!


Montana’s geography and complex topography raise intriguing questions about the source of its monarch breeding population. Western breeding grounds are roughly defined as being west of the Rocky Mountain Divide, while the eastern monarch population’s breeding grounds generally lie in the prairies and badlands to the east. But just how permeable are these boundaries and how does Montana’s topographic relief influence western and eastern monarch movements and seasonal distributions? And how do Montana’s extensive river systems and rich river valleys of milkweed and nectar plants influence migratory connectivity between the western and eastern populations? There is much to learn about the relative importance of Montana to the western monarch population, but it is fair to say the contribution, though likely modest, only adds to the species’ viability and resiliency across its western range.


by Maggie Hirschauer


How many monarchs are in western Montana? When are they here? Where do they come from, and where do they go? These are just a few of the questions the Bitterroot Monarch Project hopes to answer.


The Bitterroot Monarch Project (BMP), supported by the MPG Ranch, initiated monarch and milkweed monitoring across the northern 40 miles of the Bitterroot Valley in the summer of 2019. The project emphasizes documenting milkweed resources in the valley, restoring milkweed through seed distribution and root cuttings, monarch biology and phenology research, and educational outreach opportunities.


Enthusiasm, surprise (Monarchs in Montana!?), and interest from the surrounding community has grown the BMP into a network of volunteers each championing their own milkweed site. This summer 13 volunteers are surveying milkweed weekly for monarchs following the methods of the Monarch Larva Monitoring Project (MLMP).  All of their data will be reported on the MLMP website for researchers to use nation-wide and will be compiled to gain a better understanding of the butterfly’s phenology in our region.


Only a handful of adult butterflies were seen across the Bitterroot Valley this summer. However, volunteers’ hard work surveying milkweed has paid off. BMP volunteers documented monarchs in Stevensville and Missoula, coinciding with Beth’s observations of monarchs in the National Bison Range (see article below). The project is now raising 5 chrysalides and will tag the butterflies before release in conjunction with Dr. David James’ Pacific Northwest Tagging Project. Earlier in July a female butterfly visited a beautiful patch of showy milkweed (Asclepias speciosa) along the roadside in Stevensville. She spent over an hour with BMP volunteers laying eggs on buds and leaves across the patch. Volunteers collected 16 eggs but unfortunately none of them hatched. We suspect the female was unmated and laid non-viable eggs. As disappointing as this was, we hope documenting this phenomenon may be important in understanding factors of the species’ ecology.


One of the best ways to contribute to monarch conservation is through planting native milkweeds and other native nectar sources. Engaging children and students in these efforts is critical! Thankfully, there are so many great organizations in Missoula making educational outreach easy through partnerships. The BMP shared the mysteries and magic of monarchs with the Missoula Butterfly House and Insectarium’s Summer Bug Camps over 2 weeks in August… Ready, Set, Migrate! Kids participated in relay races mimicking the migration across western states and contributed milkweed observations for the BMP community science project. 


In the age of COVID-19, the BMP reached out to hundreds of Montana students (Grades 3-6) via monarch focused webinars with the help of the Montana Natural History Center’s FieldStudies program.


In 2019, the Missoula International School students voted to make the monarch butterfly the school’s permanent mascot. This summer the BMP helped one school patron establish the MIS Pollinator Test Garden which now hosts over a dozen plants native to western Montana. This garden will be accessible to all MIS students to observe pollinators, learn about native plants and gardening principles, and contribute to monarch community science data collection.


by Maggie Hirschauer


Restoration and healing the land can be a powerful tool. The Montana Audubon Center’s facility in Billings rests on a 54-acre reclaimed gravel mine bordering the Yellowstone River. Staff and volunteers made showy milkweed (A. speciosa) a focus in their gardens and this year their hard work has been validated. MT Audubon Center staff noticed a male flying around the center near the end of June and a female flying a few weeks later.


That’s when the fun started. Between the facility’s showy milkweed and a volunteer’s milkweed across town, volunteers found 22 monarch larvae between July and August. One caterpillar was parasitized by flies, but all others are healthy and will fly onward to continue the migration. At the time of writing (August 17), nine adults have already eclosed at the Center and were released. The Center's staff have raised 13 indoors and are currently monitoring another 5 outside.


The Center plans to create volunteer milkweed monitoring programs in future years and tag the adult butterflies to learn if Billings hosts eastern or western monarchs. Finding and rearing these creatures has been an incredible experience for the Montana Audubon Center’s staff and volunteers as monarchs have never been noticed on the site before.


Volunteer Coordinator Emily Chilcoat says she’s been seeing more people in Billings posting about the monarch caterpillars. She is encouraging them to log their sightings with Journey North.



by Beth Waterbury

Located in northwest Montana, the 18,000+-acre National Bison Range sits at the south end of the scenic Mission Valley. Established by President Theodore Roosevelt in 1908, the refuge has played an important role in the recovery and conservation of bison.


The Bison Range supports a diverse ecosystem of native Palouse prairie, Douglas-fir and ponderosa pine forests, mountain shrubs, and lowland riparian areas dominated by black cottonwood, quaking aspen, and Rocky Mountain juniper. Growing within the riparian floodplain are healthy stands of showy milkweed (A. speciosa).

This summer, under a U.S. Fish & Wildlife Service special use permit, retired wildlife biologist Beth Waterbury is surveying the National Bison Range for milkweed, mapping its locations, and monitoring milkweed patches for monarch breeding activity. The purpose of the effort is to fill information gaps on the distribution of milkweeds and its use as natal habitat by western monarchs in Montana.


On July 14th, a single female adult was observed “hovering” around a robust patch of showy milkweed in the Mission Creek riparian area. A check on July 24th found five 2nd instar monarch larvae on this visited patch, and a follow-up check on August 1st confirmed six 4th instar monarch larvae. Beth will continue monitoring the cohort to see if they successfully eclose.


Her volunteer project continues through October 2020 in hope of spotting some migrating monarchs.

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Help Us Conserve the

Western Monarch

The U.S. Fish and Wildlife Service received a petition to list the monarch butterfly under the Endangered Species Act (ESA).  Their decision is due December 2020.

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