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Dead monarch butterflies lie on the ground in a Mexican forest - Source: Reuters
Dense clouds of migrating monarch butterflies used to snap
branches and cast shadows across the forests of central Mexico, but
severe weather is posing a new threat to the annual
phenomenon.
The yearly 3,200 km journey, which takes four generations of
butterflies to complete, starts in Canada and ends in the Mexican
state of Michoacan, which normally enjoys mild weather from
November to March.
Millions of the insects swarm to these arid hills each year, their
orange-and-black wings creating a flickering fog of colour that
mesmerizes locals and tourists.
"When I first saw the monarchs in their sanctuary, I thought it was
more of a plague than something beautiful," said David Bernal, a
guide at the Piedra Herrada resting place two hours drive west of
the capital, of a childhood visit.
"I was afraid. There were so many, they clouded our path."
A loss of forests and food sources has for years thinned the number
of monarchs coming to Mexico.
But scientists fear that a new pattern of punishing winter
storms may mark the start of an irreversible decline of the
transcontinental migration.
In early February, normally one of Mexico's driest months, 38 cm of
precipitation fell on hilly central regions, battering monarch
reserves with snow, sleet and freezing rain.
Fewer butterflies arrived this year than ever before and as many as
half of them are thought to have perished in February.
The snowstorms that recently buried US cities like Philadelphia
and Washington began as unseasonable Mexican rains when warm winter
air became loaded with ocean moisture.
Vanishingly small
"Populations are only so resilient," said Chip Taylor, a University
of Kansas entomologist who has studied the migrations for two
decades.
"Will butterflies come back? Yes, but the numbers will be so
vanishingly small that it may mean the end of this spectacular
phenomenon," Taylor added.
The monarchs' transcontinental to and fro is woven through local
myth since past generations saw the butterflies as returning
ancestral souls.
Today, the monarch is a proud local emblem that inspires taxi
companies and soccer teams.
In three of the past 10 winters, at least half the monarch
butterflies arriving in Mexico died due to the topsy turvy weather
that many scientists link to climate change.
Mexico will host a global climate change summit in November that
aims to set binding international goals for reducing carbon
pollution.
Even before strange weather became commonplace, the monarch was
imperilled due to a loss of food and habitat.
As they sail across the Great Plains, monarchs survive on milkweed
that is being crowded out by large-scale farming.
Meanwhile, illegal loggers clear protected land of oyamel fir trees
whose slender needles are a favourite roosting place.
President Felipe Calderon, a Michoacan native, once vowed to use
the army to halt logging, but Mexican forest set aside for monarchs
is still being picked apart by "tree theft and mafia-style
logging," said US researcher Lincoln Brower of Sweet Briar College
in Virginia.
Brower, 78, has studied monarch butterflies since the 1950s. He was
one of the first people to see the Mexican over winter sites after
they were identified by scientists in 1975, a sight he said caused
him to "practically fall on the ground."
"Now I may outlive the monarchs," he said.
