FILE - In this Nov. 25, 2007 file photo a couple of monarch butterflies perch on a tree at the Monarch Butterfly Biosphere Reserve in the central Mexican town of Cerro Prieto. On Monday Feb. 14, 2011,... more 
FILE - In this Nov. 25, 2007 file photo a couple of monarch butterflies perch on a tree at the Monarch Butterfly Biosphere Reserve in the central Mexican town of Cerro Prieto. On Monday Feb. 14, 2011, the conservation group World Wildlife Federation Mexico released a report stating that there is a partial recovery in the annual winter migration of Monarch butterflies to Mexico following a devastating 75 percent drop last year. less 
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Associated Press | Photo By Miguel Tovar, file
Wed, Feb 16, 2011 4:46 AM EST