The Iconic Monarch's Migration

This is a map of the monarch butterfly migration routes in North America. Monarch butterflies travel down to California and Mexico for the winter months, and then fly back up to the United States for the summer months.

A Monarch Butterfly's Continental Journey:

This is the most fascinating part about monarch butterflies. Monarch butterflies migrate from the Canadian region to the Mexico region and California region. A monarch butterfly can fly up to 3,000 miles in these journeys! They migrate to areas where they can rest and escape the harsh winters up north in these warmer places in California and Mexico. They can form clusters and clusters and clusters on trees (Monarch Joint Venture)!

There are two different migratory monarch groups: the western monarchs and the eastern monarchs. Eastern monarchs fly mostly from the northeast-most parts of Canada and the United States down into the wintering grounds in central Mexico. In contrast, western monarchs fly mostly from the northwest-most parts of Canada and the United States down into the wintering grounds in California (Monarch Joint Venture).

Monarch Butterfly Resting Areas:

Monarch butterflies usually rest during the winter season in oyamel fir forests. These forests are located in high elevations on mountains in Mexico. Monarch butterflies rely on the ideal temperatures and ideal humidity provided by the climate of this forest to have a perfect settlement to rest. In addition, the strong branches of oyamel fir trees allow for an appropriate amount of monarch butterflies to nestle in them, allowing thousands of monarch butterflies to group together on one branch of the tree (U.S Forest Service).

But one monarch butterfly does not settle by itself alone. Thousands and thousands of monarch butterflies group together in clusters, all huddling together. This is called roosting. Similar to how penguin colonies huddle together during blizzards, monarch butterflies also huddle together to provide warmth for each other. In addition to providing each other warm, monarch butterflies also rely on warming up from the heat of the Earth's solar radiation, striking monarch butterflies to warm them up (U.S Forest Service).

How Monarch Butterflies Migrate

We now know where monarch butterflies migrate, but how do monarch butterflies know where to navigate to? Well, monarch butterflies have directional aids that help them in knowing where to go. One of these is the Earth's magnetic field. Earth generates a magnetic field, causing magnetic force to be a universal force prevalent throughout the planet. Monarch butterflies use this force to help them migrate down south and then back up north again. Specifically, recent studies show that they are built with an "internal compass", allowing them to be provided direction on where to go to migrate (Guerra, Gegear, Reppert 2014).

However, magnetic fields are not the only way of how monarch butterflies can reach their migration places. They also can use the direction of the sun, specifically at wavelengths of 380 to 430 nanometers. Combining this magnetic energy with the sun's solar energy, monarch butterflies can use special receptors on their antennae called magnetosensors to allow their "internal compass" to direct them where they need to go (Guerra, Gegear, Reppert 2014).