One of the world's greatest wildlife spectacles is under threat because environmental projects to protect the monarch butterfly are failing, a leading expert has warned.
The flight of clouds consisting of millions of the orange and black butterflies migrating thousands of miles across North America to the mountains of Mexico is considered one of the great natural wonders of the world.
Scientists have warned for years that the butterflies are under threat because genetically modified crops are destroying the weeds and flowers they feed on and lay eggs in, and illegal logging is decimating their winter habitat high in the Mexican mountains.
Professor Lincoln Brower, who has been studying the species for more than half a century, claims a Mexican government scheme to protect the forests where the butterflies spend the winter is failing. He will visit Britain later this month to draw attention to the problems he has observed. 'The illegal logging has not only accelerated; it has become a lot more intense, with dozens, up to hundreds, of people involved in big logging operations,' he told The Observer.
As well as research showing 44 per cent of the forest in the wintering areas had been thinned, degraded or removed since 1971, Brower said on a trip to the region this year he was informed of a 'massive kill-off' where the butterflies had returned to a badly damaged part of the forest.
The monarchs rely on the canopy to be their 'umbrella and blanket' and protect them from the freezing winter rains and sub-zero temperatures.
'If you even thin those forests you're degrading their over-wintering habitat, then they start freezing to death - they get wet and when they are wet they freeze easily,' said Brower.
Brower said that he had flown over several hundred square kilometres of the region and not found a single new area where the butterflies spent winter - though experts are not sure why the species returns to the same sites every year, even when they are damaged.
'We don't have any evidence for it, but we think butterflies are in some way marking their areas they spend the winter in,' he added.
Alfonso Ramos, federal prosecutor of environment for the Mexican government, said: 'The Mexican state is trying to reduce the problem of illegal logging. However, there are organised gangs that create conflict in the forests by cutting trees illegally. We have even created security committees to protect these areas.'
Other experts have cast doubt on claims that butterflies are affected by the existence of GM crops.
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