Every December, scientists visit the 12 sanctuaries and measure the area of forest covered by monarchs. The measurements are made in hectares. One hectare is 2.47 acres, about the size of two and a half football fields.

Try This! Monarch Math
Using the latest population estimate of 2.48 hectares in winter 2017/2018:

Monarchs from across eastern North America flew to Mexico and occupied an area smaller than _________ football fields!