Written by Maggie Heraty, Graduate Student, NC State University

Spring is here in North Carolina, with warmer weather, green leaves popping out on tree branches, and flowering plants showing their spring blooms. Not only are we humans feeling more awake and energized with the longer hours of sunshine, but animals are also responding in kind to the taste of spring. Among them is one of the most iconic animals of North America, which begins a spectacular migration each year during the spring season: the monarch butterfly (Danaus plexippus).

Each year, these orange and black beauties make a massive trek across North America, from where the “winter generation” spent the cold months of the year to where their children and grandchildren spend the warmer spring and summer. Scientists are still actively studying monarch migration to uncover the mysteries of where exactly monarchs travel and how they survive their massive migration journey. However, some patterns in the monarch migration are well-known, including the fact that there are several distinct monarch populations occupying different areas of North America.

The majority of monarchs—including the ones we see here in North Carolina—are a part of the “Eastern population”, named for the fact that their migration path is through eastern North America (1, 2, 3, 4). These monarchs spend the winter months, from early November to mid-March, in the Monarch Butterfly Biosphere Reserve in Mexico, a UNESCO World Heritage Site located in a mountainous region of Michoacán and México States (5, 6). This area is home to oyamel fir (Abies religiosa, also called sacred fir) forests, the preferred roosting site for monarchs. Oyamel fir trunks and branches can be completely covered by the butterflies during the winter, and branches often bend under the weight of thousands of monarchs clustered together. The mountains and oyamel fir forests of south-central Mexico provide a unique microclimate for the monarchs that is sufficiently warm and humid for their winter survival, ensuring they can conserve their fat reserves and avoid drying out during diapause (a process similar to hibernation). Throughout the winter, the monarchs also share body heat with one another by clustering tightly together on the trees.

In late February and into March, as temperatures begin to rise and hours of daylight increase, the monarchs become more active. During this time, they begin to mate and often move to lower elevations in the mountains of Mexico. In mid-March, they start their migration northward through Mexico and into the southeastern United States. As they fly, they search for milkweed plants (Asclepias spp. and Cynanchum spp.), where the butterflies lay their eggs and which monarch caterpillars rely on as their sole food source (11, 12).

Once they’ve laid their eggs, this set of monarchs—the “winter generation,” sometimes called generation 1—soon dies, but from their eggs hatch a new group of monarch caterpillars: generation 2. These caterpillars feed on the milkweed plants where they were born, steadily grow larger, and eventually form a chrysalis, in which they undergo the elaborate change from caterpillar into butterfly. Once generation 2 emerges as butterflies, they are ready to fly north along the migration path. From March to June, they make their way further into the southeastern U.S. and into the Midwest. You can see monarchs arriving here in North Carolina during this time!

During their migration journey, monarch butterflies feed on the nectar of many flowering plants (including milkweed, but also many other plants) growing in natural areas, along roadsides, on farms, and in people’s gardens. These nectar plants provide the food that monarchs need to sustain themselves as they fly long distances. Just like their parents, generation 2 will breed and eventually find milkweed plants where they lay their eggs. Over the course of the spring and summer, the monarchs go through another 2 to 3 non-migratory generations (13).These generations spend the warm months of the year in the Midwest, the Northeast, and all the way into southern Canada, which is the northernmost limit of milkweed plants (14, 15).

The migration cycle of the Eastern population of monarchs reaches its final chapter in the fall, from approximately mid-August to November. The last generation in the annual cycle, what some scientists call the “super” generation of monarchs, are born. This super generation is biologically and behaviorally different from their spring and summer ancestors. These monarchs are prepared to make the longest migration flight of all, from Canada and the northern U.S. all the way back to the oyamel fir forests of Mexico. These monarchs have never been to Mexico themselves; rather, they are the descendants of the monarchs that spent last winter in Mexico. Depending on how many spring and summer generations there were, they could be the great-great-grandchildren of the monarchs overwintering the previous winter! Amazingly, these butterflies instinctively know the way back to the overwintering grounds of their ancestors. Their trip from northern latitudes down to Mexico can be as much as 3,000 miles long (16). To survive the journey, the butterflies glide along air currents to conserve energy and feed upon flower nectar to gain weight. Once they reach their overwintering sites in central Mexico, the monarchs huddle together on oyamel fir trees and enter winter diapause.

This is when the annual monarch cycle begins anew. This group of monarchs becomes the new “winter generation.” Not only are these monarchs called the “super generation” because they make a long flight during autumn, but also because these same butterflies survive the winter, “wake up” from winter diapause, and then make a return flight to northern Mexico and southeast U.S. to lay eggs at the start of next spring. That’s right, they are the new generation 1! All in all, these overwintering monarchs live 6 to 9 months, unlike their spring and summer counterparts which live just 2 to 5 weeks.

In addition to the Eastern population of monarchs, there are also smaller populations in North America that do not make quite as extensive of a migration. In fact, there is a subset of the Eastern monarchs that is based in Florida, which scientists believe do not migrate at all (17). These monarchs likely spend the entire year in Florida, with no need to migrate because of the favorable year-round weather conditions in the area.

There is a “Western population” of monarch butterflies that does indeed migrate, but within a narrower range than their eastern cousins (18). Western monarchs stay within the United States, keeping west of the Rocky Mountains. These monarchs overwinter along the coast of California, where they spend the colder months clustered in forests dominated by Monterey pine (Pinus radiata), Monterey cypress (Hesperocyparis macrocarpa), and the non-native blue gum eucalyptus (Eucalyptus globulus) (19, 20). In the spring and summer, Western monarchs leave their California wintering grounds and migrate throughout western states like Arizona, Utah, Idaho, Washington, and Oregon. These monarchs are less well-studied than the Eastern monarch population, and scientists believe that a subset of Western monarchs may still make their way to overwintering grounds in Mexico and then return to the western U.S. for spring and summer.

Finally, there are also populations of monarchs elsewhere in the world. Though monarchs are native to North America, they can now be found in 90 countries, islands, and island groups, including in South America and Oceania (21). Scientists are still studying how monarchs have reached other regions of the globe, but it’s likely that humans have played a role in their spread over the last 200 years.

When considering the vast area that monarchs cover, it is almost unimaginable that monarch butterflies can survive and successfully migrate year to year. Across all portions of their range, monarchs face a multitude of threats, and their populations are at risk (22).The International Union for the Conservation of Nature (IUCN) lists the migratory monarch butterfly (Danaus plexippus ssp. plexippus) as a “vulnerable” species, but across their range, monarchs have disparate protections depending on the country they are in (23, 24). Here in the United States, in December 2024, the U.S. Fish and Wildlife Service proposed listing monarchs as “threatened” under the Endangered Species Act, a change that would increase monarch protections here in the U.S. A final decision on the monarch status has been postponed by the Trump administration (25, 26, 27, 28).

Researchers and community scientists estimate that monarch populations have declined greatly from their historic levels (which was in the hundreds of millions), first recorded in the 1990s. “A decline of more than 80% has been seen in central Mexico and a decline of more than 95% has been seen in California” according to the Xerces Society for Invertebrate Conservation. This decline is caused by a combination of factors, including habitat loss, the use of pesticides, declines in native plants (milkweed and nectar plants), disease, and climate change.

Across the United States and Canada, there is a considerable amount of urban, suburban, and agricultural development that threatens monarch populations. This development transforms natural areas into residential and agricultural spaces, paving or plowing over large swaths of land that monarchs use as habitat. This land conversion can lead to the destruction of areas that monarchs rely on for refuge and for their food plants.

In addition, the use of herbicides, insecticides, and genetically modified (GMO) “Roundup Ready” crops has increased in agricultural and residential areas in both the U.S. and Canada, all of which contribute to monarch declines (29). “Roundup Ready” crops do not themselves harm monarchs, but rather, these crops are able to survive applications of Roundup (an herbicide that contains the active ingredient, glyphosate) on agricultural fields, whereas milkweed and other native nectar plants cannot. The use of Roundup in agriculture has reduced farmers’ reliance on tilling as a weed control system, which in turn helps decrease soil erosion, fossil fuel use from heavy machinery, and soil compaction, among other benefits (30). Unfortunately, the unintended consequences are having an effect. According to the World Wildlife Fund, the use of Roundup in conjunction with GMO crops has led to the elimination of “99% of the milkweed that once grew in corn and soybean fields.” Meanwhile, the use of neonicotinoid insecticides since the early 1990s has also made “U.S. agriculture 48 times more toxic to insects” like monarchs (31).

In Mexico, monarchs also face a number of threats. Though monarch overwintering sites are protected within the UNESCO Monarch Butterfly Biosphere Reserve, the oyamel fir forests are threatened by human activities taking place in and around the reserve. In 2025 alone, UNESCO reported that wildfire, impacts from tourism, land conversion for farming, and illegal activities (like logging and mining) were all on the list of threats that affected the reserve (32). According to the IUCN, “more than 27,800 people, the owners of the territory, live within the reserve, distributed across 68 ejidos (a kind of communal agricultural land), 12 Indigenous communities, and 41 small private properties…Paradoxically, when the reserve was declared a protected area, local people who depended on the forest for their livelihoods were left with no income—resulting in an increase in illegal logging and the degradation of the forest” (33). Many organizations, including Alternare and SAbERES project, now work with the local communities around the Biosphere Reserve to train community members in sustainable agriculture and construction, support their livelihoods, and promote climate change adaptation among ejidos (34, 35). Their success has helped to greatly decrease habitat destruction in the area.

Unfortunately, the oyamel fir forests that monarchs rely on in Mexico are also facing stress from the changing global climate. Oyamel firs are adapted to the cool, moist conditions in the mountain elevations in Michoacán and México States. With climate change, the annual temperatures of this region are gradually warming, and droughts are becoming more frequent. Scientists have studied how these changes might impact the oyamel fir forests over the next century, and projections show that by the year 2090, 96.5% of the area occupied by oyamel firs will no longer be suitable for the trees’ survival (36). These projections cast a chilling prognosis for the future of monarch populations that rely on these forests.

Thankfully, organizations and scientists are working together across international boundaries to conserve oyamel fir forests and protect monarch butterfly populations. As one example, researchers from the University of Michoacán are helping promote these forests by planting oyamel firs on higher mountain peaks, near their current locations in the Monarch Biosphere Reserve (37, 38, 39). Already, oyamel firs are slowly spreading upslope in the mountains, taking advantage of the cooler temperatures at higher elevations. However, the pace of oyamel fir reproduction upslope cannot match the pace of climate change, so scientists are helping the oyamel fir move uphill through “assisted migration” and are tracking if the monarchs will follow. Additionally, each year, the World Wildlife Fund–Mexico and its partners conduct an annual census of monarch populations in Mexico. Just last month (March 2026), they published hopeful results, showing an estimated 64% increase in the area occupied by overwintering monarchs in Mexico compared to last year, a useful proxy showing an increased size in the monarch population (40, 41).

This report gives hope for the many collaborative conservation efforts taking place across the range of monarchs. However, much work is still to be done. The population numbers in Mexico are still below the historic levels of monarchs. Additionally, the population of Western monarchs has unfortunately not shown an upward trend; in November 2025, Xerces Society recorded the third lowest population numbers of Western monarchs ever recorded (42). To continue to protect monarchs and their habitat, the key will be continued collaboration between governments, academia, non-profit organizations, volunteers, and everyday people, like you and me.

Here in North Carolina, small actions can make a big difference for migrating monarchs. Now that it’s spring, you might soon have a monarch butterfly cross your path while on a walk or sitting outside. If you do, take a moment to honor the amazing migration that that one butterfly has taken to get here. It has likely not been an easy journey, and we sure are lucky to see these monarchs here in the Southeast.

There are a multitude of ways we can all pitch in to ensure these spectacular creatures can not only survive, but thrive. Here are some opportunities you can take part in to help support monarch butterflies. You can find even more ways to help through the plethora of resources available online about monarchs, including many listed in the Bibliography section of this post.

• Get involved in community science efforts to study and protect monarchs. Monarch Joint Venture provides a comprehensive list of volunteer programs here, and you can join the International Monarch Monitoring Blitz that takes place each summer in late July (43, 44).
• Plant milkweed and nectar-providing plants around your home, neighborhood, school, and/or workplace.
  • There are a variety of milkweed plants native to different regions of North America, and World Wildlife Fund provides a list of native milkweeds that can be planted locally to support monarchs (45).
  • Xerces Society provides a great list of nectar plants for monarchs across their range, which can be purchased from local nurseries near your home (46).
• Reduce the use of herbicides and insecticides around your home and community.
• Educate others about monarchs and their amazing life cycle.
• Donate to organizations, both here and abroad, that are studying and protecting monarchs and monarch habitat. A handful of these organizations have been referenced in this article and have websites listed in the Bibliography below, and many more can be found online.

The next time you see a monarch in North Carolina, you’re not just seeing a butterfly—you’re witnessing one step in a continent-wide journey that depends, in part, on all of us.

1. Eastern Monarch Conservation. (2026, March 17). Xerces Society for Invertebrate Conservation.
2. Monarch Status: Annual Cycle. (n.d.). Monarch Butterfly Fund. Retrieved March 26, 2026.
3. Monarch (Danaus plexippus). (2026, February 2). U.S. Fish & Wildlife Service.
4. Monarch Butterfly Migration and Overwintering. (n.d.). Forest Service, U.S. Department of Agriculture. Retrieved April 2, 2026.
5. Monarch butterflies. (n.d.). World Wildlife Fund. Retrieved March 26, 2026.
6. Monarch Butterfly Biosphere Reserve. (n.d.). UNESCO World Heritage Centre. Retrieved March 26, 2026.
7. Parcerisa, C. (2024, September 26). A Monarch Migration Timed to Mexico’s Day of the Dead. National Wildlife Federation.
8. Gonzalez, C. (2020, April 2). More Than Monarchs: Understanding Traditions linked to Monarch Butterflies. Monarch Joint Venture.
9. Casa de la Cultura Mazahua. (2026).
10. The Latin American Post Staff. (2025, December 29).Mexico Monarchs Meet Mazahua Pride as Tourism Rewrites Michoacán Futures. LatinAmerican Post.
11. Pocius, V. M., Debinski, D. M., Pleasants, J. M., Bidne, K. G., Hellmich, R. L., & Brower, L. P. (2017). Milkweed Matters: Monarch Butterfly (Lepidoptera: Nymphalidae) Survival and Development on Nine Midwestern Milkweed Species. Environmental Entomology, 46(5), 1098–1105.
12. New research adds insight about milkweed species. (2017, October 25). Iowa Monarch Conservation Consortium.
13. Carnegie-Schadde Memorial Public Library. (2020, May 1). Monarch Butterfly Biology and Conservation with Dr. Karen Oberhauser [Video recording].
14. Monarch Migration. (n.d.). Monarch Watch. Retrieved March 26, 2026,.
15. National Wildlife Federation Monarch Recovery Strategy. (n.d.). National Wildlife Federation. Retrieved March 26, 2026.
16. Restoring Habitat for Monarch Butterflies. (n.d.). National Wildlife Federation. Retrieved April 1, 2026.
17. Howard, I., & Slusser, K. (2025, February 6). 5 Monarch Migration Facts. Xerces Society for Invertebrate Conservation.
18. Western Monarch Conservation. (2026, March 17). Xerces Society for Invertebrate Conservation.
19. Monarch butterflies in California. (2024, December 11). U.S. Fish & Wildlife Service.
20. Griffiths, J. (2014). Monarch Butterfly (Danaus plexippus) Tree Preference and Intersite Movement at California Overwintering Sites. Master’s Theses.
21. Global Distribution. (n.d.). Monarch Joint Venture. Retrieved April 6, 2026.
22. Overwintering Habitat Loss. (n.d.). Monarch Joint Venture. Retrieved April 2, 2026.
23. IUCN Standards and Petitions Committee. 2023. Danaus plexippus ssp. plexippus (amended version of 2022 assessment). The IUCN Red List of Threatened Species 2023: e.T194052138A246096271. Accessed on 01 April 2026.
24. Monarch Butterfly Conservation. (2026, March 17). Xerces Society for Invertebrate Conservation.
25. Richmond, T. (2025, December 12). Trump administration delays decision on federal protections for monarch butterflies. AP News.
26. United States Endangered Species Act Status. (n.d.). Monarch Joint Venture. Retrieved March 26, 2026.
27. Save the monarch: Status under the Endangered Species Act. (2025, March). U.S. Fish & Wildlife Service.
28. Monarch Listing Decision. (2025, December 19). Monarch Watch.
29. The great monarch migration: A unique phenomenon under threat. (2025, April 23). World Wildlife Fund.
30. Cerdeira, A., & Duke, S. (2006). The Current Status and Environmental Impacts of Glyphosate-Resistant Crops: A Review. Journal of Environmental Quality, 35, 1633–1658.
31. Bolt, C., & Friedman, S. (n.d.). Protecting pollinators by reducing pesticides. World Wildlife Fund. Retrieved April 1, 2026.
32. Centre, U. W. H. (2025). State of Conservation (SOC 2025) Monarch Butterfly Biosphere Reserve (Mexico). UNESCO World Heritage Centre.
33. Communities building the future of the monarch butterfly. (2026, March 26). IUCN, International Union for Conservation of Nature and Natural Resources.
34. Alternare, A.C.(n.d.). Retrieved April 2, 2026.
35. SAbERES. (n.d.). Retrieved April 2, 2026.
36. Sáenz-Romero, C., Rehfeldt, G. E., Duval, P., & Lindig-Cisneros, R. A. (2012). Abies religiosa habitat prediction in climatic change scenarios and implications for monarch butterfly conservation in Mexico. Forest Ecology and Management, 275, 98–106.
37. Sáenz-Romero, C., Osuna-Vallejo, V., Herrejón-Calderón, P., Pérez-Cruz, L. A., Joaquín-Juan, M. G., Cruzado-Vargas, A. L., O’Neill, G. A., Zacarías-Correa, A. G., Manzanilla-Quijada, G. E., Lindig-Cisneros, R., Blanco-García, A., Endara-Agramont, Á. R., & Lopez-Toledo, L. (2024). Establishing monarch butterfly overwintering sites for future climates: Abies religiosa upper altitudinal limit expansion by assisted migration. Frontiers in Forests and Global Change, Volume 7-2024.
38. In Mexico, moving a forest to save monarchs. (2022, March 7). American Forests.
39. Hartley, S. (2024, October 18). Saving Mexico’s fir forests could help monarch butterflies. ScienceNews.
40. Monarch butterfly population increases 64%. (2026, March 17). World Wildlife Fund.
41. Lovett, J. (2026, March 17). Monarch Population Status. Monarch Watch Blog.
42. Moranz, R., & Black, S. (2026, March 17). Eastern Monarch Butterfly Numbers Increase, but Remain Below Historic Levels. Xerces Society for Invertebrate Conservation.
43. Community Science Opportunities. (n.d.). Monarch Joint Venture. Retrieved April 2, 2026.
44. Pasos, M. (n.d.). International Monarch Monitoring Blitz. Commission for Environmental Cooperation. Retrieved April 2, 2026.
45. Monarch milkweed finder. (n.d.). World Wildlife Fund. Retrieved March 26, 2026.
46. Adamson, N. L., Fallon, C., & Vaughan, M. (n.d.). Monarch Butterfly Nectar Plant Lists for Conservation Plantings. Xerces Society for Invertebrate Conservation. Retrieved April 1, 2026.