April 2016 - Parks & Recreation - 56

MONARCHS

of their eastern counterparts - they do
migrate, but do not make as long a migration. Their migratory patterns are
generally different than the eastern population.] The root cause was a massive
loss of habitat, primarily from the
disappearance of milkweed plants in
the vast corn fields of the heartland.
The so-called " corn belt " forms the
most important habitat on the monarch migration highway that literally
hundreds of millions of monarchs
previously traveled on their migration north. Genetically modified
corn that is resistant to the primary herbicide used for weed control,
glyphosate, rapidly replaced all other types of unmodified corn. Often
called " Round-up ready " for its ability to resist the weed-killing effects of the herbicide Roundup,
this corn does not die when
sprayed with glyphosate, but
all weeds do die, including
milkweed. For monarchs,

this proved to be devastating.
Because of the rapid embrace of
this GMO corn, which now totals
almost 90 percent of all U.S. corn
and more than 95 percent of soybean crops, a huge swath of what
was once high-quality monarch habitat has disappeared. More than 150
million acres of monarch habitat has
been lost and in that timeframe, what
was once a population of 1 billion
monarchs fell to barely 50 million.
Many other factors also played a role
- extreme weather, logging of the
Oyamel firs in the Mexican wintering
forests, loss of other non-agricultural
habitat and other factors.
Fate of Monarchs Balanced
on a Knife's Edge
Since the monarch population
crashed from its highest number in
1996, combined with legitimate fears
about the future viability of the entire
monarch migration, there has been a
massive outpouring of public support
that has spurred a dramatic conservation effort to save this much-loved

Parks across the country are developing innovative projects to provide monarch habitat.
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species. Recent developments point
to just how delicate is the balance of
the monarch's recovery.
First, the good news: After 20 years
of long-term decline in the eastern
population of monarchs, the estimates of the 2016 wintering monarchs
showed the total population was up
significantly - 225 percent from the
previous year. However, even though
the numbers were up by a significant
percentage, 2016 marks one of the
lowest counts ever recorded and there
may be more bad news ahead.
A just-published study in the journal Scientific Reports by the Scripps
Institution of Oceanography at the
University of California, San Diego,
and the U.S. Geological Survey, estimates that there is a " substantial
probability " of an extinction-type
event for the entire population of
monarchs if they were subjected to
events such as severe winter storms
or extended periods of extreme heat
or drought, or other environmental
causes. The researchers estimate the
probability of the complete loss of
this subset of the monarch population from such an event as between
11 percent and 57 percent. If the
monarch population were decimated in such a manner, recovery of the
species would be impossible.
Chip Taylor, head of Monarch
Watch and one of the authors of the
study says, " There is annual variation in the monarch population and
that is natural. The problem is that
we can always have unanticipated or
unexpected bad weather. " For example, Taylor noted, there was a heavy
late winter storm in Mexico this year
that caused the blow-down of trees
and other damage in the monarch
wintering areas. " There were clusters of monarchs in the trees covered
with snow, but we were fortunate. A
lot of our monarchs had already left
the wintering forests. This is just one

April 2016 - Parks & Recreation

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