EUROPEAN
observers have long admired colorful painted lady butterflies (Vanessa
cardui) and have wondered what happened to them at the end of each summer.
Do they simply perish with the onset of cold weather? Fresh research reveals an
extraordinary story. The butterflies make an annual journey between northern
Europe and Africa.
Researchers combined
results from sophisticated radar with thousands of sightings reported by
volunteers across Europe. The results revealed that as the summer ends,
millions of painted lady butterflies migrate south, mostly flying at an
altitude of more than 1,600 feet (500 m)—therefore hardly ever seen
by humans. The butterflies wait for favorable winds, which they ride at an
average speed of 28 miles per hour (45 km/h) on the long trip to
Africa. Their annual migration is up to 9,300 miles (15,000 km) long,
beginning from as far north as the fringes of the Arctic and terminating as far
south as tropical West Africa. The trip is almost double that of the North
American monarch butterfly. It takes six successive generations of painted
ladies to complete the round-trip.
Professor Jane Hill of
the University of York, in England, explains: “The Painted Lady just keeps
going, breeding and moving.” Annually, those steps take the whole population
from northern Europe to Africa and back again.
“This tiny creature weighing
less than a gram [0.04 oz] with a brain the size of a pin head and no
opportunity to learn from older, experienced individuals, undertakes an epic
intercontinental migration,” states Richard Fox, surveys manager at Butterfly
Conservation. This insect was “once thought to be blindly led, at the mercy of
the wind, into an evolutionary dead end in the lethal British winter,” Fox
adds. Yet this study “has shown Painted Ladies to be sophisticated travelers.”
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