Facts on Migration
The monarch butterfly is the most commonly seen butterfly in North America. It has a distinct appearance with orange and black patterns on its wings. It makes an appearance roughly from March to October, when the weather is warm and the daylight has a longer stretch.
Migration Begins
As delicate as the monarch butterfly appears, it has the strength to migrate long distances -- as much as 2,500 miles. The journey begins as early as late as August and ends by the first frost. The monarch butterfly migrates to Mexico and southern California, depending on their location in the northern part of the United States and southern Canada through the summer. The migration occurs each year with a collection of three to four generations. The female monarch butterflies deposit eggs in the process of migration.
Migration is essential for the monarch butterflies. Change to colder weather impairs their abilities and put their survival at risk. Monarch butterflies cannot survive temperatures below freezing. Cold weather also impacts their flying abilities and may cause paralysis. Food supply also becomes an issue. During colder weather, the nectar supply dwindles. A new home in warmer weather must be found to ensure food supply is plenty.
It's believed the monarch butterfly detects time for migration based on weather change and noticeable differences with the daylight shortening. Upon detecting these warning signals, migration begins with the assistance of wind to push them toward their winter home.
Roosting
Some monarch butterflies do not survive the migration process, and there are also those that settle in winter roosting sites. The butterflies essentially cluster together on pine and eucalyptus trees in California and ovamel trees in Mexico. Their wings overlap one another to form a shingle effect. This formation offers protection, warmth and a shield against rain and wind.
Roosting sites for the monarch butterflies can be found primarily along the Californian coast and the Sierra Madre Oriental Mountains in Mexico.
The Return From Migration
The return from migration begins in March. The larvae from the laid eggs, left by the female monarchs during migration, join the returning pack as a new generation. This cycle of migration and reproduction is continuous, year after year, to ensure the existence of monarch butterflies.
While the monarch butterflies do what is natural for them, migrating and reproducing, there have been changes to land that many believe has impacted the monarch butterfly population. Roosting sites have diminished, leaving the insects with limited outlets to resort to.
Various conservation efforts are in place to assist with the challenges facing monarch butterflies. Canada, Mexico, and the United States, are cooperating through the North American Monarch Conservation Plan. This plan seeks to protect the monarch butterflies and its habitat for migration. A collective effort between these countries is needed because migration depends on conservation of habitats in all three countries.
For more information about the monarch butterfly, their migration, and conservation efforts, please refer to the links listed below:
Cape May Bird Conservatory: The Monarch Monitoring Project conducted offers a view into the incredible journey the monarch butterflies take to migrate and looks into issues of conservation and research.
Monarch Butterfly USA: Find information about the lifecycle and migration of monarch butterflies. The site also offers information about milkweeds and provides resources for teachers and children to learn more about this insect.
National Geographic: Read up on the lifecycle and migration of monarch butterflies and find quick facts about the insect.
The Monarch Migration: Information is offered on why the monarch butterflies migrate, where they can be found at certain times of the year, and what dangers are posed to these insects.
NOVA: Find an online video entitled "The Incredible Journey of the Butterflies," which documents the monarch butterflies' journey to their sanctuary destination in Mexico.
World Wildlife Fund: Under the Species category, get an inside look into monarch butterflies. Read about their migration and the World Wildlife Fund's monarch butterfly conservation strategy.
