The orange and black Monarch butterfly is a well known and recognizable species. But in 2022, it was listed as endangered. As a group, these spectacular migratory creatures move about 2,485 miles (4,000 kilometers) across North America, a journey that can take several generations of butterflies. They move from parts of Mexico and California every year to other parts of the United States and Canada. But logging and deforestation has ruined many monarch habitats, or placed them under threat. Climate change, which can increase droughts and wildfires that disrupt Monarch habitats, as well as dams and poaching, cause more trouble for monarchs.
The western population of Monarch butterflies is thought to have declined almost completely, or 99.9 percent. It's estimated that there were once about 10 million butterflies in this group in the 1980s. But by 2021, it had been reduced to 1,914 butterflies. The eastern population is larger, but has also declined by about 84 percent between 1996 and 2014. Some experts are concerned that there are not enough butterflies left to sustain the populations.
So how can we help?
Milkweed is a plant that provides struggling monarchs with a lifeline. Monarchs only eat milkweed, and it is also disappearing. Research has shown that the addition of native milkweed to backyard and urban gardens can help support the butterflies, and add more butterflies and caterpillars to the local area. The findings have been reported in Frontiers in Ecology and Evolution.
This study determined that when city gardens added milkweed, then caterpillars and monarchs arrived. "In this study, we found that monarchs can find the milkweed, wherever the milkweed is, even if it's in planters on balconies and rooftops," said first study author Karen Klinger, a Geographic Information Systems analyst in the Keller Science Action Center at the Field Museum. "Milkweed gardens can be in all shapes and sizes, and any milkweed garden can contribute habitat for monarchs."
Monarchs lay eggs as they migrate, and there next generation keeps the migration going. These butterflies will get to southern Canada. When summer ends, a new super generation of monarchs is born, and they will fly all the way south where they will survive through the winter, Klinger explained.
The monarchs need milkweed all along their migratory path. But the extensive use of pesticides in the Midwest has eliminated a lot of wild milkweed, and monarch habitat, added Klinger.
Now, urban gardens might help the butterflies recover from this loss.
After training about 400 citizen scientist volunteers, the researchers got data about monarch activity in the Chicagoland area. The work showed that older milkweed tended to attract more butterflies than younger milkweed plants, and when a variety of blooming plants grew along with the milkweed, there were more butterflies. But any little bit helps, the researchers added.
"Plant the species that works the best for you and your garden," said Klinger. The Mobilizing Our Neighborhoods to Adopt Resilient Conservation Habitats (MONARCH) Act was also recently passed in Illinois by Governor JB Pritzker (D), so HOAs cannot prohibit the planting of native or pollinator boosting gardens.
Sources: Field Museum, Frontiers in Ecology & Evolution