[Pollinator] New study reveals high extinction risk for western monarch butterfly population

[Sarina Jepsen]

A new paper describing a Population Viability Analysis for the western
monarch population was published today: http://www.
sciencedirect.com/science/article/pii/S0006320717304809.

This study reveals that western monarchs are far more endangered than
previously thought, and that, in the 1980s, there were at least 10 million
monarchs overwintering on the California Coast (compared to ~300,000
currently).

Here is the media release:



*Monarch butterflies disappearing from western North America **New study
reveals that western monarch decline is more severe than decline in East*


VANCOUVER, Wash. - Monarch butterfly populations from western North America
have declined far more dramatically than was previously known and face a
greater risk of extinction than eastern monarchs, according to a new study
in the journal *Biological Conservation*.


“Western monarchs are faring worse than their eastern counterparts,” said
Cheryl Schultz, an associate professor at Washington State University
Vancouver and lead author of the study. “In the 1980s, 10 million monarchs
spent the winter in coastal California. Today there are barely 300,000.”


Schultz adds, “This study doesn’t just show that there are fewer monarchs
now than 35 years ago. It also tells us that, if things stay the same,
western monarchs probably won’t be around as we know them in another 35
years.”


Migratory monarchs in the west could disappear in the next few decades if
steps aren’t taken to recover the population, Schultz said.


Like eastern monarchs, which overwinter in Mexico, western monarchs have a
spectacular migration. They overwinter in forested groves along coastal
California, then fan out in the spring to lay their eggs on milkweed and
drink nectar from flowers in Arizona, California, Nevada, Oregon,
Washington, Idaho and Utah. They return to their coastal overwintering
sites in the fall.


In the 1990s, residents of coastal California became alarmed that a once
common butterfly seemed to be disappearing. The Biological Conservation
study indicates that those concerns were justified. The researchers
combined data from hundreds of volunteers who have participated in the
Xerces Society’s Western Monarch Thanksgiving Count since 1997 with earlier
monarch counts conducted by amateur and professional butterfly enthusiasts
in the 1980’s and early 1990’s. They then predicted the monarch
population’s risk of extinction over the next several decades.


Emma Pelton, endangered species conservation biologist at the Xerces
Society for Invertebrate Conservation and co-author of the study, said the
research will help conservationists better understand the extinction risk
of western monarchs.


“Scientists, policy makers and the public have been focused on the dramatic
declines in the well-known eastern population, yet this study reveals that
western monarchs are even more atrisk of extinction,” Pelton said. “We will
need significant conservation action to save monarch butterflies in the
West.”


The precise causes of the decline in western monarchs are not yet clear,
but the loss and modification of its habitat and pesticide use across the
West, where monarchs breed, are likely culprits, the researchers said.
Climate change and threats to coastal California overwintering sites likely
also play a role, they said.


The U.S. Fish and Wildlife Service, which funded the study, is currently
considering whether to list the monarch butterfly as a threatened species
under the Endangered Species Act.


Elizabeth Crone, Tufts University professor and a co-author on the study,
says that “The hard part of being a conservation biologist is documenting
species declines. The exciting part is figuring out how to help declining
species recover. In the 20th century, we brought bald eagles back from the
brink of extinction by limiting use of DDT. If we start now, we can make
the 21st century the era in which monarchs return to our landscapes.”


*Sarina Jepsen*
Director of Endangered Species and Aquatic Programs, The Xerces Society
<http://www.xerces.org/>
Co-Chair, IUCN Bumblebee Specialist Group | bumblebeespecialistgroup.org



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