As monarch butterflies migrate through the United States, the Monarch Watch research program teaches Kansans how to conserve their declining populations
Kristen Baum, professor of ecology and evolutionary biology, senior scientist with the Kansas Biology Survey and director of Monarch Watch at the University of Kansas, knows a lot about monarch butterflies. Currently, she’s keeping an eye on the U.S. Fish and Wildlife Service’s (USFWS) recent proposal to list monarchs as a threatened species.
If the monarch is so designated, the USFWS will create recovery plans, provide money for conservation and identify critical habitat. The USFWS accepted 90 days of public comment to hear from farmers, conservationists, scientists and landowners—or anyone else with an opinion or concern about monarch populations or how protection efforts might affect agriculture and land use. Because monarchs have a large range across the U.S., any new regulations will affect many farms and ranches.
“There’s lots of chaos we’re concerned about,” Baum says.
Since 1992, Monarch Watch has been tracking monarch migration across Kansas. What was supposed to be a short-lived project has become an internationally renowned program in monarch research, education and conservation.
There are two main monarch populations in the U.S.—the eastern migratory population, which breeds as far north as southern Canada and migrates to central Mexico for the winter, and the western migratory population, which overwinters along the coast of California. Kansas’ monarchs are part of the eastern migratory population. “They overwinter in the high-elevation oyamel fir forests of central Mexico,” Baum says. The oyamel forest ecosystem is one of Mexico’s most endangered, with only 2% of the original forest remaining.
Sometime in February or March, the WWF-TELMEX Telcel Foundation Alliance and the National Commission of Protected Natural Areas in Mexico announce the overwintering numbers, which are in the millions. “The traditional approach is they go out and find the tree that’s farthest upslope that’s occupied by monarchs. Then, they measure the distance to all the trees around the monarch cluster and estimate the area,” Baum says. The enclosed area is calculated in hectares, which is about the size of 2.5 American football fields. The currently accepted estimate is 21.1 million monarchs per hectare.
The last overwintering season (2023–2024) was the lowest on record, at .9 hectares, which means fewer than 20 million monarchs made it through migration to overwinter in Mexico. Thankfully, the population rebounded some during the more recent 2024–2025 season, at 1.79 hectares.
“They’ll spend about five or so months on those overwintering grounds, and then they’ll start moving north in late February or early March. We’ll get our first records of monarchs in Texas, usually sometime in March,” Baum explains.
Those returning monarchs will lay the first generation of eggs in Texas and sometimes the surrounding states. The monarchs that grow from those eggs continue to move north and to reproduce, including in Kansas. “We’ll usually get our first reports of monarchs in Kansas sometime in April,” Baum says.
During the spring and summer breeding season, the nonmigratory monarchs live only two to six weeks, depending on the conditions. But the migratory monarchs may live as long as nine months. “The difference in lifespan is fascinating and shows how much energy is required for reproduction. The last generation of monarchs that emerge in the fall are in reproductive diapause and instead focus on migration,” Baum says.
Monarchs need different resources depending on the time of year. During fall migration, monarchs rely on blooming, nectar-producing plants. But in the spring, one nectar-producing plant is critical to the monarch’s survival as it’s the only plant on which they lay their eggs—milkweed.
“Milkweed is what caterpillars can eat, so it becomes very important—it’s the only host plant for monarch caterpillars, and their only food source,” Baum says.
Because of the nationwide decline in milkweed, Monarch Watch encourages Kansans to join the Monarch Waystation Registry and create their own Monarch Waystation habitats by planting milkweed and other nectar sources in home or school gardens, parks, zoos and nature centers.
Of course, climate change affects most wildlife, including monarchs. “Most of the monarch lifecycle is tied to temperature,” Baum says. The availability of milkweed in Texas is critical to monarch migration, but milkweed growth depends on temperature and rainfall, both of which are affected by climate change. Temperature also affects monarch egg and caterpillar development—it slows down in cooler weather and speeds up when it’s warmer. If monarchs move north too quickly, they can get caught in cooler weather, slowing their progression. Finally, the weather affects southern migration—when it’s too hot, monarchs stop migrating.
Fortunately, people love monarchs, Baum explains. “Monarchs are very charismatic,” she says. “People can relate and connect to them.”
Monarch tagging kits are $15 and available for preorder from Monarch Watch (monarchwatch.org/tagging); they will ship in late July. Download the Monarch Watch mobile app at monarchwatch.org/app to keep track of tagging data. For more information about starting your own Monarch Waystation, visit monarchwatch.org/waystations.
Upcoming Monarch Watch Events
Monarch Watch Spring
Open House & Plant Fundraiser
Saturday, May 10 (8 a.m. to 2 p.m.)
Foley Hall, 2021 Constant Ave., Lawrence
Monarch Watch Fall Open House
Saturday, September 13 (9 a.m. to 2 p.m.)
West Campus, 2021 Constant Ave., Lawrence
Monarch Watch Tagging Event
Saturday, September 20 (8 a.m. to noon)
Baker University Wetlands Discovery Center
1365 N. 1250 Road, Lawrence
