The Eastern population of the monarch butterflies in North America continues to suffer long-standing declines. This increases the species' risk of extinction that could reach a culmination in the next 20 years, a new study found.
A joint research from the U.S. Geological Survey and the Scripps Institution of Oceanography at the University of California, San Diego found that the Eastern population of the monarch butterflies decreased by 84 percent to the winters of 1996-1997 and 2014-2015. They estimated that the species have an 11 to 57 percent chance of quasi-extinction in the next 20 years.
A quasi-extinction is when rehabilitation is impossible because there are only a few remaining individuals in the species left. While the surviving individuals may continue to live for several years, extinction is inevitable.
Lead study author and Scripps scientist Brice Semmens said that because of the varying annual monarch populations, which is quite dependent on climate and several factors, efforts to increase the average population is the most important thing mankind can do to provide the iconic butterflies a much-needed extinction buffer. The research was published in the Scientific Reports journal on March 21.
For instance, when the analysis ended, World Wildlife Fund Mexico along with several partner institutions documented a sizable increase in the population of monarch butterflies since 2015. Unfortunately, the succeeding winter storm affected the recent surge. This suggests that despite a good winter, a higher population average is required to lower the long-standing quasi-extinction risk.
In their analysis, the researchers measured the monarch butterflies' population size using the geographical area that the colonies cover during their winter stay in Mexico. By 2020, the U.S., Canada and Mexico intend to increase the wintering monarchs' population so it can occupy about 15 acres by that time. To date, the monarch's population has increased to almost 10 acres.
During the 2014-2015 winter, the population was nearly 2.8 acres. It reached a record low during the 2013-2014 winter at about 1.7 acres.
"Monarchs are what we call an environmental indicator," said Canton-based Roaring Brook Nature Center director Jay Kaplan. "It tells us something is radically wrong with our environment and that we [humans] could be affected as well." Kaplan is also a Connecticut Butterfly Association member.
Photo: Paul Stein | Flickr
