Reports that 22 million monarch butterflies have been slaughtered in Mexico have been greatly exaggerated, according to the World Wildlife Fund and American Monarch researchers.
鈥淚t鈥檚 been overblown,鈥� says Monica Missrie, monarch butterfly co-ordinator for the WWF in Mexico City. 鈥淚t was probably two or three million.鈥�
Between 100 and 500 million monarch butterflies migrate every year, travelling about 5000 kilometres from Canada to Mexico and back. They stay in Mexico鈥檚 forests for about 5 months in the winter before heading back north.
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Homero Aridjis, head of the environmental lobby Group of 100, told Reuters it was believed that loggers had sprayed forests in the Cerro San Andres and Las Palomas areas with pesticides. The death of the Monarchs would re-open the sanctuary area to logging, he said.
Cold snap
But Missrie told New 杏吧原创 that the mass deaths were probably caused by cold, not pesticides. Recent heavy snowfalls in the area would have been particularly devastating to butterflies trying to winter in the heavily logged forest, she says. A similar cold snap in 1996 also killed millions of Monarchs.
鈥淚t can look like they were sprayed,鈥� says Missrie, because the butterflies鈥� fat comes to the surface of their wings when they die, giving them an oily feel. The WWF has sent biologists into the field to collect samples and they expect to confirm the cause of death within a few weeks.
The butterfly colonies are also much smaller than Aridjis鈥� estimate, Missrie says, because the forests were heavily logged in the past and the butterflies have sought better homes for the winter.
Northern escape
Karen Oberhauser, from a Monarch public awareness program at the University of Minnesota, adds that many of the butterflies may have already headed north on their migration and escaped the kill.
Oberhauser says: 鈥淚f it is true, then 22 million is a big chunk.鈥�
But insect populations are known to vary wildly. Given good breeding conditions, the butterflies could make up for that 10 percent dip in their population in a single summer. But since there are still snow banks outside her window in Minnesota, she says, 鈥渋t doesn鈥檛 look good.鈥�