Environmental officials and experts are cautiously celebrating a recent rise in the monarch butterfly population, which has suffered a stark decline in recent years due to a variety of factors. The population of monarchs who made their annual trip to Mexico this past December increased three-and-a-half times from the previous year, but the totals are still far below those from two decades ago.
“This December, the butterflies covered 10 acres (about 4 hectares), compared to 2.8 acres (1.13 hectares) in 2014 and a record low of 1.66 acres (0.67 hectares) in 2013.”
Because monarch butterflies clump together densely under forest canopies when they arrive in Mexico, they are measured by the amount of land they cover rather than the individual number of insects. Researchers were optimistic at the end of 2014, when the number of acres they occupied started to rebound, and are pleased they rebounded even more this year.