[Pollinator] 'Substantial probability' of monarch extinction -- study

[Mace Vaughan]

'Substantial probability' of monarch extinction -- study

Corbin Hiar <http://www.eenews.net/staff/Corbin_Hiar>, E&E reporter

Published: Monday, March 21, 2016

There is "substantial probability" that the eastern population of monarch
butterflies could be wiped out in the near future, according to a study
published today in the journal *Scientific Reports* that could affect the
insect's status under the Endangered Species Act.

The analysis <http://www.nature.com/articles/srep23265>, conducted by
researchers at the Scripps Institution of Oceanography at the University of
California, San Diego, and the U.S. Geological Survey, estimated the
probability of a "quasi-extinction" event, where so few butterflies remain
that recovery is impossible, at between 11 percent and 57 percent over the
next two decades.

After a severe winter storm, a stretch of extreme temperatures or other
such event, a few butterflies would survive for a short time. But
extinction of the population as a whole would become "inevitable," the
study said.

There are about 150 million monarch butterflies today, down from 1 billion
in the mid-1990s. The vast majority of the remaining monarchs live in the
eastern portions of Canada, the United States and Mexico.

"The cause of the recent decline has been predominantly attributed to the
loss of breeding habitat, primarily in the U.S.," the study said.

Monarchs lay their eggs on milkweed plants, the prevalence of which has
declined with the adoption of herbicide-tolerant genetically modified corn
and soybeans, researchers noted. Those GMO crops now account for 89 percent
and 94 percent of the corn and soybeans grown in the United States,
respectively.

Other threats to the orange and black butterflies include habitat loss in
their Mexican wintering sites, climate change, insecticides, mowing
regimes, invasive species and disease.

"Increasing the average population size is the single-most important way to
provide these iconic butterflies with a much-needed buffer against
extinction," Brice Semmens, the lead author of the study and a scientist at
Scripps, said in a statement. That can best be done by creating and
restoring monarch breeding habitat, the study found.

The researchers' extinction risk estimate also differs substantially from
an earlier analysis that found there is around a 5 percent chance that
monarchs could vanish in the next century. But that study assumed monarchs
could recover if reduced to 1,000 butterflies, a population size far below
the 250,000 level at which monarchs' reproductive success begins to
diminish, the Scripps-USGS team argued.

Some conservationists hope the new study will force the Fish and Wildlife
Service to add the monarch to the threatened or endangered species list, a
move that could require the agency to limit herbicide use on millions of
acres of cropland.

"This study does put pressure on FWS to protect the monarch because it
shows that the butterfly is at risk of extinction," Tierra Curry, a senior
scientist at the Center for Biological Diversity, said in an email. "More
than 99 percent of monarchs are in the eastern migratory population."

CBD and the Center for Food Safety filed a lawsuit last month that aims to
force the Fish and Wildlife Service to determine whether the monarch
butterfly should qualify for Endangered Species Act protections (*E&ENews
PM <http://www.eenews.net/eenewspm/stories/1060033806/>*, March 10).
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