Monarch Migration is Underway!

Folks up north in places like Minnesota are already seeing lots of signs of the beginning of monarch migration. Large numbers of monarchs are seen roosting in trees and bushes overnight. A patch of nectar flowers might see 60 monarchs visiting at a time. And groups of monarchs are seen flying together, at the same height and speed, in a southerly direction. Yes, the fall migration of monarchs has begun.

 
Most of these monarchs will be headed to Mexico, to roost by the millions in the trees of places like Michoacán, Mexico. They’ll rest there during the cooler temperatures of winter after flying hundreds and, in some cases, thousands of miles. They’ll remain there until spring, when the warming sun will wake them and encourage them to journey back north again.

 
The fall migration is made by a single generation of monarchs, meaning the butterflies that leave Minnesota and other northern states will be the same ones that arrive in Mexico several months later. These same butterflies will rest during the winter, then mate in the spring and begin flying north. They will stop along the way, perhaps in Texas, where they will lay eggs and die. Their offspring will continue the journey north when they emerge as butterflies, stopping somewhere a bit further along the route to repeat the process. It takes several generations of butterflies, each living only a few weeks, to make the spring migration.

But the fall butterflies are different. They live as many nine months to complete their extraordinary journey. Somehow, in their genetic code perhaps, they pass along the signals to their offspring to tell them where to fly in the spring. Much of this is still a mystery, as it is often is with the phenomenon of migration.

 
Here in peninsular Florida, we have a year-round resident population of monarchs that don’t migrate. This is both good and bad. We enjoy these butterflies every month of the year, which is great for us. But if a disease or weakness makes its way into the population, it’s likely to become widespread very quickly, without the advantage of outside breeding with other butterfly populations to strengthen the resident population again.

Some butterflies do migrate to and from Florida, though, and you may see an increase in monarchs in the months ahead. You can help these butterflies by planting milkweed, their host plant. Click here for directions on creating a Certified Monarch Waystation.

If you live in northern states, look for monarch festivals and activities in your community as the butterflies pass through. You can track migration by visiting and contributing data to Journey North, which features detailed maps of spottings and weekly updates. Monarchs are beloved across the country, so you’re sure to find a way to learn about and celebrate these amazing fliers!

Roosting Monarch Photo Credit: Judith Finley via Journey North