Monarch butterflies have made a significant comeback in their wintering grounds in Mexico after suffering serious declines in the past several years, investigators announced Friday.

Migratory monarch butterfly populations rebounded to 68 percent of a 22-year average in 2015, occupying almost 10 acres of forest in their Mexican hibernation areas, as indicated by a new survey. They covered only 2.8 acres in 2014, and the record low was just 1.66 acres in 2013.

"We are seeing the beginning of success," Daniel Ashe, director of the U.S. Fish and Wildlife Service, said at a World Wildlife Fund news conference in Mexico on Friday. "Our task now is to continue building on that success."

Every year around October, the orange-and-black butterflies migrate between 1,200 to 2,800 miles from Canada through the U.S. to spend the winter in the temperate mountain forests of Michoacán State and Mexico State.

During this journey, monarchs face manifold hazards, including deforestation and logging, pesticides, climate change and loss of milkweed, which is the only plant that they use to breed along the way, as explained by the World Wildlife Fund (WWF). Larvae feed and grow on milkweed before metamorphosing into butterflies.

The annual migration pattern is a biologically inherited trait, and no single butterfly lives to make the full round trip. It remains a mystery how they make their way back to the same forested swath each year, The Guardian noted.

While the acreage increase indicates a potential for recovery, the numbers remain far below the nearly 45 acres in which monarchs spent the winter months in the peak year of 1996, after which the species lost 90 percent of its population.

"What the scientific monitor is showing is that there is an apparent recovery in the last two years, which is why this is good news," said Omar Vidal, director general of the WWF in Mexico, according to The New York Times. "But the threats for the butterfly, for their migration, continue."

"Now more than ever, Mexico, the United States, and Canada should increase their conservation efforts to protect and restore the habitat of this butterfly along its migratory route," Vidal concluded.

The U.S. is trying to replace about 7.5 million acres of milkweed through planting projects as well as regulations of pesticide use. In Mexico, where illegal logging is a considerable threat, local farmers have been provided with uniforms and equipment by the government's environmental watchdog, Profepa in order to monitor a 140,000-acre reserve territory that encompasses most of the monarchs' hibernation area.

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