Florida study finds monarch butterflies declined 80 percent since 2005 | tbo.com

Florida study finds monarch butterflies declined 80 percent since 2005 |
tbo.com
https://www.tbo.com/news/environment/wildlife/Florida-study-finds-monarch-butterflies-declined-80-percent-since-2005_173359609
Florida study finds monarch butterflies declined 80 percent since 2005
[image: Lincoln Brower, an internationally known expert on monarchs,
designed and led the 37-year study, persuading the family that owns the
Florida pasture to let the scientists visit every spring. He died in July
at age 86. [Photo courtesy of Cassie Evans/Sweet Briar College]]
<https://www.tbo.com/storyimage/TB/20181107/ARTICLE/311079572/AR/0/AR-311079572.jpg?MaxW=2000&cachebuster=758595>
Lincoln Brower, an internationally known expert on monarchs, designed and
led the 37-year study, persuading the family that owns the Florida pasture
to let the scientists visit every spring. He died in July at age 86. [Photo
courtesy of Cassie Evans/Sweet Briar College]
[image: Monarch butterflies migrating back to the U.S. from Mexico stop off
in Florida and spawn a new generation. Young monarchs form inside a
chrysalis like this one and then emerge ready to continue the long journey
to other parts of North America. [Florida Museum of Natural History]]
<https://www.tbo.com/storyimage/TB/20181107/ARTICLE/311079572/EP/1/1/EP-311079572.jpg?cachebuster=429966>
[image: Scientists counted monarch caterpillars like this one, as well as
capturing adult butterflies, on a 20-acre parcel near Gainesville over 37
years to determine the population trend. [Florida Museum of Natural
History]]
<https://www.tbo.com/storyimage/TB/20181107/ARTICLE/311079572/EP/1/2/EP-311079572.jpg?cachebuster=838442>
By Craig Pittman, Times Staff Writer
Published: November 7, 2018
Updated: November 8, 2018 at 11:26 AM

Every year thousands of monarch butterflies dance through the air over
North Florida, traveling between their winter refuge in Mexico and their
regular homes along the U.S. Atlantic coastline. The colorful pageant
attracts flocks of tourists who are eager to bear witness to this sprightly
migration.

Every year, though, there have been fewer and fewer of the princely insects
to see.

A new University of Florida study — at nearly four decades, the longest of
its kind — has found that the number of caterpillars and butterflies in
North Florida has been declining since 1985.

Since 2005, the numbers have dropped by 80 percent.

"It’s alarming," said associate professor Jaret Daniels, a co-author of the
study.

He pointed out that if a beloved and widely known species such as the
monarch can be pushed so easily toward extinction, imagine how much more
imperiled are other, less well-known ones.

"It exemplifies all the issues we’re having to deal with in conservation,"
he said.

The scientists involved in the study say the causes of the decline are not
entirely clear, but they believe there are two major factors at work.

One is the destruction — by development or agriculture — of areas that had
been planted with native milkweed, the favorite food of young monarchs. The
other is the widespread use of a herbicide called glyphosate, often applied
to farmers’ fields to kill weeds. One of the weeds it kills is milkweed.

*READ MORE:**
https://www.tampabay.com/news/environment/wildlife/Davis-Islands-woman-surprised-by-100-cocoons-now-working-to-save-the-monarchs_170949651.
*
<https://www.tampabay.com/news/environment/wildlife/Davis-Islands-woman-surprised-by-100-cocoons-now-working-to-save-the-monarchs_170949651>

The study was launched 37 years ago by an internationally known monarch
expert named Lincoln Brower. He died this summer at age 86, just before the
study was published in the Journal of Natural History.

Brower began studying monarchs in the 1950s. He was instrumental in
locating the fir trees in Mexico where they spend the winter before heading
back for Florida. In their winter home, about 80 to 100 miles west of
Mexico City, the trees are thick with the orange insects and when they flap
their wings, the sound is like thousands of leaves rustling.

"It has the most complicated migration of any insect known," Brower told
the *Chicago Tribune* in 1998. "Somehow they know how to get to the same
trees every year. It’s a highly specific behavior that is unique to the
monarch butterfly."

During their return trip to the U.S., a new generation of monarchs is born
en route. They grow from larvae to caterpillars, then turn into butterflies
to continue the rest of their flight.

That’s why checking on their population every time they landed in North
Florida allowed scientists to determine what was going on with their
population numbers.

"Florida is kind of a staging ground for the recolonization of much of the
East Coast," Daniels said. "If these populations are low, then the northern
populations are going to be at a similar abundance level."

The most famous spot in Florida to watch monarchs is St. Marks National
Wildlife Refuge, which sponsors an annual Monarch Butterfly Festival every
fall. That catches the butterflies on their way south.

Under Brower’s direction, a team of scientists closely monitored how many
monarchs showed up each spring heading north. Their selected site was a
single herbicide-free cattle pasture in Cross Creek, onetime home of
acclaimed Florida author Marjorie Kinnan Rawlings, who wrote *The Yearling*.

"Lincoln made the connection with that family 37 years ago and they’ve been
incredibly gracious to continue to allow us access," Daniels said.

At the study site 20 miles south of Gainesville, the team gathered every
year to examine the pasture’s milkweed plants for any caterpillars. They
also captured adult monarch butterflies to check the growth or decline of
the population.

The 37 years they spent doing this is roughly the equivalent of 140
generations of monarchs.

One finding of the study: Monarchs time their departure from Mexico in the
spring so it coincides with the optimal growth of milkweed in Florida and
other Southern states. While adult monarchs can eat a variety of plants,
the young ones’ diet consists of nothing but milkweed. The plants contain
toxins that they store up to ward off predators.

Florida is home to 21 native species of milkweed. Three types are best for
the monarchs, Daniels said: swamp milkweed, pinewoods milkweed and, of
course, butterfly milkweed.

Although Brower has died and the study has been published in a scientific
journal, the work will go on, Daniels said. The hope is that the monarch
migration will continue too.

*Contact Craig Pittman at [email protected] <[email protected]>. Follow
@craigtimes.*

More Information

ALL ABOUT THE MONARCH

Scientific name: Danaus plexippus

Origin of common name: Early North American settlers saw the orange wings
and named the butterfly "monarch" because King William III was also known
as William of Orange.

Size: Wingspan is 3.7 to 4.1 inches

Food: Milkweed

Lifespan: 6 to 8 months

Migration: Monarchs are believed to be the only butterflies that migrate.
They can travel between 50 and 100 miles a day. Their annual migration of
up to 3,000 miles takes about two months.
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