The migration of animals or birds from one side of a continent to the other is a well-known phenomenon in nature. But in most cases it’s a specific generation that completes the whole journey from beginning to end. What makes the monarch butterfly’s journey so unique is the fact that it takes four to five generations to complete the migration route across North America. Every year monarchs fly from Canada in the north to Mexico in the south, a journey that spans all of eastern North America.
Why do they migrate?
Two reasons:
- They are not able to survive the cold conditions up north, so they migrate to warmer overwintering sites down south.
- In spring and summer, the plants their larvae need to feed on do not grow down south, forcing them to go back north again.
How do they know where to go?
Although more research is necessary to find out exactly how they determine their direction, scientists believe they use a combination of directional aids such as the magnetic pull of the Earth, geographical landmarks, the position of the sun and other weather factors such as wind direction and air pressure. Instinct also plays a role and new research has indicated that they chemically mark trees and other beacons for the next generation to find the path.
Monarch butterfly facts
Scientific name: Danaus plexippus
Distribution: North America, the northern parts of South America, Bermuda, Cook Islands, Hawaii, Cuba, Caribbean Islands, Solomon Islands, New Caledonia, New Zealand, Papua New Guinea, Australia, New Guinea, Sri Lanka, India, Nepal, the Azores, the Canary Islands, the Philippines and North Africa
Size: Their wingspan ranges between 8.9 and 10.2cm
Description: The upper sides of their wings are tawny-orange with black veins and margins. White spots are visible in the wing margins
Text: Johann Theron
The full article appears in the June issue of AnimalTalk.
