Monarchs of Florida

Florida Monarch butterflies might be considered lucky, just like our 'Winter Friends', because they live in a climate that is mild to warm most of the year. In these temperate conditions it is warm enough that the Monarch butterfly instinct to migrate away from cold temperatures is not triggered. Monarchs in peninsular Florida get to skip an up to 3,000 mile journey and just continue flapping around the state.

In those areas of Florida where milkweed keeps growing and the temperatures remain above freezing you can find Monarchs in every month of the year. Here in Tampa Bay we have not had significant freezing temperatures this winter, so we still have wild Monarchs cruising through the outdoor butterfly gardens. These butterflies will continue to mate and reproduce so long as the weather stays mild.

Do Monarchs Migrate to Florida?
Some Monarch butterflies found along the Eastern coast of North America may make their way south into Florida rather than continuing their journey on to Mexico. These butterflies will overwinter in Florida along with the other winter species of butterflies. 

However, some Monarchs do migrate through Florida on their way to Mexico. Each year the St. Marks National Wildlife Refuge near Tallahassee hosts a Monarch Butterfly Festival where visitors can see Monarch butterflies gathered in large numbers preparing to fly the rest of the way to Mexico. Debate still remains regarding if these butterflies continue their journey by land of fly across the Gulf of Mexico.

Do Florida Monarchs Migrate North?

When asked if Monarch butterflies that reside in Florida over winter will migrate north again, butterfly expert Dr Karen Oberhauser had this to say: 

We don’t know. It appears that the monarchs that migrate to Florida may just stay there, making this population what is known as a “sink population”; butterflies fly into it from other areas, but don’t return to the other areas. 

Journey North Ask an Expert: Karen Oberhauser

 Negatives of a Sink Population
One thing that an up to 3,000 mile migration does ensure is that Monarchs that arrive in the Mexican overwintering sites are fit and healthy. Diseased, weak and sometimes even undersized Monarch butterflies will be unable to complete the grueling migration. So, each Spring, this incredibly healthy group of butterflies mates and starts heading north, laying eggs and producing a second healthy generation. Each year, this process culls out Monarchs that are not strong enough to survive.

In our "sink population" of Florida, our Monarchs don't have to test their physicality by migrating far away. The weaker or diseased members of the population have about the same access to breeding as healthy Monarchs. Because of this, diseases and parasites like Ophryocystis elektroscirrha (OE) can be found in high percentages within non-migrating populations. This particular parasite can leave Monarchs smaller in size and shorten their lifespans because the butterfly is just weaker than a healthy population. Although OE is found throughout migrating populations too, non-migrating sink populations have a higher incidence of infection. Serious infections of OE can cripple a Monarch during metamorphosis, leaving them not fully formed and unable to emerge as an adult butterfly.