The number of monarchs overwintering in Mexico has plunged to a new low, with only 1.65 acres of forest covered with clustering butterflies. This record low compares to a peak of 51.8 acres recorded in 1996. At 20 million butterflies per acre, this year's population is estimated at 33 million monarchs compared to the peak of 1 billion in 1996.
Monarch numbers are down and people are wondering why. This article examines the factors that caused the decline during the past year and the downward trend over the past decade. Also, see how you can help.