As the days grow shorter and the weather gets colder, both plants and animals adjust to seasonal changes. Some animals, such as chickadees, nuthatches, and field mice switch their food to what is available, such as seeds. Other animals, like groundhogs and bears hibernate. And still others including Canada geese and warblers migrate.
Surprisingly, another animal that migrates is the endangered Monarch Butterfly, sometimes up to 3000 miles! According to Monarch Watch, Monarch butterflies are the only butterfly that travels these amazing distances.
Monarch Migration Facts
While Monarch Butterflies west of the Rocky Mountains migrate to Southern California, Monarchs from the east travel to mountains in central Mexico. There are several generations of Monarchs every year, but only the fall generation makes this incredible trip. While spring and summer generations of Monarchs mate and lay eggs, the fall Monarchs emerge from their chrysalises ready to fly extended distances. They even gain body fat on their trip south, which helps them survive the winter in Mexico.
No one knows how these Monarch butterflies know to migrate to the same location as their great-great grandparents. Astonishingly, they sometimes even find the same tree!
So why do these insects travel these amazing distances? Like all insects, Monarchs are cold-blooded, and cannot survive the freezing temperatures. So they travel to where they can survive the winter. The oyamel fir forests of Mexico’s Transvolcanic mountains provide the exact conditions that the Monarchs require. The high elevations provide cool air which slows the Monarchs’ metabolism. This preserves the stores of fat they need to travel back north. Fog and streams provide water and the trees provide protection from rain wind, and snow.
When spring arrives, these amazing animals start their trek back north, mating and laying eggs on milkweed plants along the way. Several generations breed in their summer locals before the journey starts over again.
Sadly, Monarchs are now considered endangered. According to the Xerces Society for Invertebrate Conservation, North American populations have declined by 90% since the 1990’s. This is largely due to habitat destruction, both in Mexico and the US.
What you can do
The good news is that you can help endangered Monarch butterflies! In addition to supporting conservation organizations, here are a few things you can do at home:
- Plant milkweed (Asclepias species). Milkweed is the only food source for Monarch caterpillars and lack of milkweed is a major contributor to habitat loss. Butterfly Milkweed (A. tuberosa) and Swamp Milkweed (A. incarnata) are both beautiful, garden-worthy perennials which add color and life to your garden. Additionally, Bloodflower (A. curassavica) can be found in the annual section of well stocked garden centers, while Common Milkweed (A. syriaca) can be used in natural areas.
- Use Integrated Pest Management and avoid pesticides on your property
- Support organic and regenerative agriculture
- Assist in monitoring Monarch populations.