Which way did that butterfly go?
The flight of the butterflies is the longest known distance insect migration on Earth – and it’s been occurring for thousands of years. Monarchs sense certain topographical features, avoiding both large bodies of water and tall mountains. Instead, they choose cool valley passes between mountains.
Several migration routes in central southern Canada lead down through the central U.S. Several others start in western North America and merge with central ones. The majority of Monarchs who survive obstacles and predators manage to thread a geographical needle, hitting a 50-mile wide gap of cool river valleys between Eagle Pass, Texas, and Del Rio, Texas, and then wind their way to a dozen specific high mountain peaks in central Mexico where they roost. After resting there for several months, the same generation returns north to Texas and other parts of the southern United States, where the females lay hundreds of eggs.
While it is a rare sight, monarch butterflies can sometimes go off course due to storms! Read about how a monarch butterfly recently showed up in the Dorset, U.K. here: http://bbc.co.uk/newsround/19559249/
In July 2012 CBC’s The Current dedicated a segment to the monarch butterfly and its unusual 2012 migration patterns. Listen here to learn more: http://www.cbc.ca/player/Radio/The+Current/ID/2253783608/
Based on original map design created by Paul Mirocha (paulmirocha.com) for Monarch Watch.
Strong yet susceptible
Monarchs have specialized body parts to help it navigate and migrate long distances. They orient themselves both in longitude and latitude, a unique ability, and can travel up to a mile high.
To conserve energy, Monarchs ride along prevailing winds and catch rising thermal waves, helping them travel great distances in a single day. They hide from the rain and will die if exposed to freezing temperatures and ice storms. Cold and moisture are deadly to the fragile butterflies and can result in hundreds of millions dying at once. Surprisingly, when the monarchs arrive in the Mexican Sanctuaries, they are heavier and fatter than they were when they began their journey. They are able to store their lipids during their journey, so they can have fat stores while in Mexico.
The most intriguing mystery still remains – how do the Monarchs know to go to these particular mountaintops amongst thousands?