Animals

Monarch Butterfly Population May Quadruple in Mexico

Actions taken by the United States, Mexico and Canada to protect the migratory species are having a positive effect.

Monarch butterflies wintering in Mexico could nearly quadruple in number this year thanks to actions taken by the United States, Mexico and Canada to protect the migratory species, authorities said Thursday.

After years of sharp decline, the three countries agreed at a summit in February 2014 to form a working group to foster the insect's survival.

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More than a year later, the measures "are having an effect," Mexican Environment Minister Rafael Pacchiano said at a news conference at the Piedra Herrada monarch reserve alongside US Interior Secretary Sally Jewell.

Pacchiano said authorities hope the orange and black butterfly will occupy between three and four hectares (7.4 and 9.9 acres) of the mountain forest, located in central Mexico, this season.

"This is almost four times (the population) that arrived in the previous season," Pacchiano said, before a tour of the mountaintop, where hundreds of butterflies were resting or flying around fir trees.

The insect occupied 1.13 hectares of forest in the past season, better than in 2013-2014, when the population hit an all-time low of 0.67 hectares.

The goal is to reach six hectares by 2020. This compares to a high of nearly 19 hectares in 1996-1997.

Butterflies On The Verge Of Collapse: Photos

Officials measure the size of the population by the area they cover instead of individual numbers.

The falling population has been blamed on illegal logging in their Mexican wintering grounds and the drop in milkweed on which they feed due to the use of pesticides in the United States.

Pacchiano said Mexican authorities have launched "important" operations to combat illegal logging while Jewell said the United States is working on replanting milkweed in three million hectares of land and designating pesticide-free areas.

A monarch touches down in the ecosystem of this purple thistle flower. | iStockphoto/Thinkstock

"Mexico, the US and Canada have many species that don't know our political borders, that cross the borders freely," Jewell said.

The goal, she said, is "225 million monarch butterflies returning right here to Mexico every year. We believe we can get there by working together and it sounds like we may be on our way, we hope."

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The number of butterflies has dropped by 90 percent in the last 25 years.

The butterflies travel 4,000 kilometers (2,500 miles) from Canada to spend the winter in a mountain reserve straddling the states of Mexico and Michoacan.

They usually arrive at their nesting ground between late October and early November and head back north in March.

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While the Mexican government has announced arrests of illegal loggers in recent months, the World Wildlife Fund (WWF) reported in August a drastic increase in clandestine tree cutting in some reserves.

In the Michoacan community of San Felipe de los Alzati, 19.13 hectares were affected by illegal logging in the 2014-2015 monarch butterfly season.

This was four times higher than the 5.18 hectares that were hit by such illegal activities in the communities in the 2013-2014 season.

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The arrival of monarch butterflies means jobs for 250 families at the Piedra Herrada sanctuary.

Miguel Dominguez, 52, has worked as a guide there for more than 15 years.

"Tourism falls year after year," Dominguez lamented as he pulled a horse that took visitors up the mountain. "It's good for us that the governments are working together and not fumigating the milkweed, so that more butterflies arrive in Mexico."

A monarch touches down in the ecosystem of this purple thistle flower.

Between September and November, North American monarch butterflies make a staggering fall migration that may take as many as 3,000 miles to complete. In appreciation of that arduous journey, let's enjoy a few pictures of these winged beauties and learn a bit about their amazing trip.

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During the summer, it's breeding season, and ordinary monarchs will live about 2-5 weeks, during which they'll mate and lay eggs. Those eggs will become the next generation, each successive generation flying a bit further north than the last. All told, there are four generations of monarchs per year. It's the fourth, and last, generation that's special. Born in the fall, they are hard-wired to migrate. As such, they don't become reproductive right away. (They'll do that later, on the return flight north, having lived for as long as nine months!) The migration kicks in once temperatures drop. Monarchs don't handle cold weather very well. Too deep a chill affects their ability to fly. So when cooler air and shorter days come in late summer and early fall, it's time for them to pack their bags and head south.

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Generally, monarchs west of the Rocky Mountains will overwinter in central and southern California, while those east of them will head for Mexico's Michoacan Mountains. They use the same overwinter sites year after year. Sometimes even the same tress, notes

Monarch Watch

, a site devoted to all things monarch butterfly. The precision of their navigation is still a bit of a mystery. It's thought they find their way using the sun and a kind of solar compass in the brain. But last summer

we learned

that they may also be using Earth's magnetic field to continue the journey on cloudy days.

Monarch Butterflies Use Magnetic Field To Navigate

As they continue southward, only flying during the day, the butterflies will make pit stops to rest and to nectar. Astonishingly, they gain weight along the way, even though the journey is unspeakably long and draining for something so small and delicate.

Don't Move A Monarch Butterfly, It Could Get Lost

These amazing navigators make the trip on wings just 3 to 4 inches across. While they can fly quickly if something startles them, they more typically pilot along as if sailing on the winds.

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Along the way, adult monarchs will dine on the nectar of a great many plants. Wild carrot, lilac, and alfalfa to name just a few. And, as we can see, when it's time to crash, they don't mind living in close quarters.

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The eastern U.S. monarchs that head to Mexico will overwhelmingly make their way to the Monarch Butterfly Biosphere Reserve, a World Heritage site that is home to millions of monarchs from October through March. These monarchs have reached their destination and are just kicking back in Mexico.

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Once February and March arrive, spring is near. And -- guess what? -- it's time for these well-traveled monarchs to gear up and make a return flight north, as temperatures there warm up. Only now do they become reproductive. As they head back north, they will lay eggs on milkweed to seed a new generation. Their descendants will return to the same overwintering sites from which they returned. Ain't nature grand?

Strange And Beautiful Butterflies: Photos