Western Monarch Butterflies Await Endangered Species Act Protection

Dec 19, 2020

Western monarch butterfly populations have seen a shocking decrease of 99% in recent years.

The U.S. Fish and Wildlife Service announced earlier this week that a petition to protect monarch butterflies under the Endangered Species Act has been put on a waiting list. 


Drastic declines in both the eastern and western populations of monarch butterflies in North America led to a 2014 petition by the Center for Food Safety, Center for Biological Diversity, and other advocates seeking endangered species classification. 


The monarch butterfly is a prolific and essential pollinator for many crops and other plants across the country, including here in Utah. 


With populations that once numbered in the hundreds of millions, the most recent counts show a disturbing decline of 85% for the eastern U.S. population and a decline of 99% for monarchs west of the Rocky Mountains. Both populations are considered to be below the minimum level where scientists estimate the migrations could collapse.


The announcement by the Fish and Wildlife Service means the butterfly’s status will be reviewed each year until either a species listing is proposed or the petition is denied.


The future looks grim for the species as the Fish and Wildlife Service has estimated up to an 80% probability of population collapse for eastern monarchs within 50 years. The western population faces an even more disturbing 96-100% probability. Fewer than 2,000 total western monarchs have been counted so far this winter during the annual tally in California.


Given the dire situation, Tierra Curry, a senior scientist at the Center for Biological Diversity, said in a press release: 


“Forty-seven species have gone extinct waiting for their protection to be finalized. This decision continues the delay in implementing a national recovery plan which monarchs desperately need. Monarchs are beautiful, they play important roles in nature and culture, and their migrations are jaw-dropping. We owe them and future generations an all-in commitment to their recovery.”


Monarch populations have dwindled as a result of the widespread destruction of milkweed, which is the caterpillar’s sole food source. The increasing use of herbicides and crops genetically engineered to withstand the plant are largely responsible. The butterflies have lost an estimated 165 million acres of breeding habitat in the United States to herbicide spraying and habitat destruction in recent decades.


Monarchs are also threatened by logging on their overwintering grounds in Mexico and California, as well as droughts and severe weather events made worse over the years by global climate change.


Other North American countries have taken steps to protect monarchs, with Canada expected to list the species as endangered under their Species At Risk Act and in Mexico, they are considered a species of special concern.