[Pollinator] More Milkweeds Located Throughout the Landscape Can Help Conserve Monarchs

[Scott Black]

News Release

June 22, 2017



Marisa Lubeck, USGS, 303-526-6694, mlubeck at usgs.gov



Daniel Stolte, University of Arizona, 520-626-4402, stolte at email.arizona.edu



Catherine Puckett, USGS, 352-377-2469, cpuckett at usgs.gov





*More Milkweeds Located Throughout the*

*Landscape Can Help Conserve Monarchs*

*New study highlights multi-pronged options to restore iconic butterfly*



*Read the paper at:
http://iopscience.iop.org/article/10.1088/1748-9326/aa7637
<http://iopscience.iop.org/article/10.1088/1748-9326/aa7637>*



 Adding milkweeds and other native flowering plants into midwestern
agricultural lands is key to restoring monarch butterflies, with milkweed
sowers from all sectors of society being critically needed for success.



In a new study by the U.S. Geological Survey, the University of Arizona and
partners, scientists developed potential scenarios for incorporating
milkweed into the Midwestern United States landscape.



They found converting marginal cropland to monarch-friendly habitat
provides the best opportunity for adding milkweed to help restore the
eastern migratory monarch population. However, in addition to agricultural
lands, the authors emphasized that planting milkweeds into other kinds of
lands, including protected areas and urban and suburban locations, may be
necessary.



With quintessential bright orange and black markings punctuated by white
dots, monarch butterflies are an iconic species. North American migratory
monarch populations east of the Rocky Mountains declined by more than 80
percent over the last two decades, due, in part, to the loss of millions of
milkweed stems in the northern U.S.



Milkweed is the only plant that provides breeding habitat and food for
monarch young, but because adult monarchs feed on the nectar from a range
of flowering plants, the U.S. Fish and Wildlife Service recommends planting
both milkweeds and nectar plants that are native to specific areas. In
addition to breeding habitat loss, factors contributing to monarch declines
include adverse weather conditions in recent years, loss of overwintering
habitat, disease and exposure to contaminants.



“The main finding of our study is that an all-hands on deck approach could
be essential to restoring the massive amounts of milkweeds needed to make
the monarch population healthy again,” said Wayne Thogmartin, a USGS
scientist and the lead author of the report. “These findings offer great
hope for citizens from all sectors working together to reverse the
substantial decline of these iconic butterflies.”



A recent USGS-led report found that more than 1.6 billion additional
milkweed stems may be needed in North America to return eastern migratory
monarchs to a sustainable population size. To determine where these
additional milkweed plants would be most effective, researchers for the new
study evaluated five land-cover sectors for their current and potential
future ability to support milkweed: protected lands, Conservation Reserve
Program lands, utility and transportation rights-of-way land, agricultural
lands and urban/suburban areas.



Thogmartin said that converting at least half of marginal agricultural land
in the Midwest to monarch friendly habitat could result in a full
population recovery. However, he said, an approach that doesn’t just rely
on agricultural lands would be more robust. The research demonstrated that
the non-agricultural sectors combined could provide as much as 800 million
stems of milkweed, leaving agricultural lands to provide the other 800
million stems.



"Encouraging urban and suburban areas to participate along with the
agricultural sector could create a crucial spark of public support and
momentum for monarch conservation across the board,” said said Laura
López-Hoffman, a conservation biologist at the University of Arizona who
co-authored the study.



The eastern migratory population of monarch butterflies, which spends the
winter in Mexico but migrates to the eastern U.S. and Canada to reproduce
during warmer months, is at risk of extinction unless its numbers increase
significantly. The U.S. Fish and Wildlife Service is considering a petition
to list monarchs under the Endangered Species Act.



Because counting individual monarchs is challenging, scientists measure
population size based on the geographic area that their colonies cover
while spending the winter in Mexico. The population size of Eastern
monarchs was 2.91 hectares, or 7.19 acres, in the winter of 2016-2017,
which is a decrease from about four hectares during the 2015-2016 season.
The U.S., Mexico and Canada aim to increase the number of Eastern monarchs
wintering in Mexico so that they occupy about six hectares, or about 15
acres, by 2020.



For more information about monarch butterfly research, please visit the
USGS Monarch Conservation Science Partnership website, the Monarch Joint
Venture website or the FWS monarch website.



The study, “Restoring monarch butterfly habitat in the Midwestern U.S.: all
hands on deck,” was published in Environmental Research Letters, and is
authored by Wayne Thogmartin, USGS; Laura López-Hoffman, University of
Arizona; Jason Rohweder, and Jay Diffendorfer, USGS; and Ryan Drum, USFWS,
and others.



USGS provides science for a changing world. Visit USGS.gov, and follow us
on Twitter @USGS and our other social media channels.



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