Each Autumn (or Fall, if you prefer), monarch butterflies, which have hatched out in the warm temperatures of summertime on North America’s eastern coast, fly more than three thousand two hundred kilometers (two thousand miles) on a journey back into their past. They have no guide and as far as scientists have yet discovered no apparent means of finding their way. However, they travel south, to the exact spot where their grandparents (not their parents) spent the winter twelve months before.
Source: Creative Commons. Wikipedia.
Somehow, they have an inborn migratory instinct, which is handed down through generations which never even made the long journey. In the summer, the monarch butterfly lives for around six weeks, so there are three or four generations during the northern warm season.
It is only the grandchildren or great-grandchildren, which survive to migrate as the autumn cold comes in. The butterflies live for the winter; way up in the Mexican mountains at a height of three thousand meters, or ten thousand feet and this discovery was only made in 1975.
Their main habitat is fields, meadows, gardens and parks and they prefer to spend the winter where there are plenty of conifer trees.
Monarch butterflies are poisonous to birds and the more poisonous the butterfly, the brighter its colors. They store milkweed poison during their caterpillar stage and this makes them distasteful or poisonous to birds and so offers a degree of protection. Their bodies contain a steroid like substance called cardenolide, which can stop the heart. The black-headed grosbeak is one bird that is not affected at all by the poison and others such as jays and some species of oriole have learned to eat the muscles, which contain smaller amounts of cardenolide.
Wintering Monarch Butterflies. Source: Creative Commons
However, when they are hibernating, hungry birds tend to forage among them and many do get eaten. The birds have learned to pick through, searching for the least brightly colored, and presumably least poisonous butterflies. The big problem is that the birds only eat a few, but they kill many as they search through for the ones they prefer to eat.
High up, in their winter quarters, at fifteen separate sites of about ten acres, they huddle together in the mountains. When the spring comes they fly north again for another breeding season.
Monarchs are also found in Bermuda, Hawaii, Southern England, Europe, New Zealand, Australia and other places in the world. The strange thing here is that not all these monarchs migrate and science has yet to discover why.
Source: Saving Monarch Butterflies
About Louie Jerome Louie Jerome is a writer and English language teacher from England. She also works part-time as an editor and does some counselling work. Life is hectic but it's never boring!
