Each year, monarch butterflies migrate over 3,000 miles to warmer winter destinations. The Rocky Mountains form a dividing line; those whose summer breeding grounds are in the Western U.S. head to the California coast and those in the East flock to the forests of central Mexico.
With a grant from the Association of Zoos and Aquariums, Butterfly Pavilion near Denver is partnering with the Government of Mexico to conserve winter habitats.
In Mexico, the butterflies cluster by the millions.
“The trees turn orange and the branches are weighed down by the weight of monarch butterflies,” said Shiran Hershcovich, a lepidopterist at Butterfly Pavilion, a zoo for invertebrates near Denver. “Even the skies almost turn orange.”
But scientists monitoring the wintering populations have noticed sharp declines. Last year, butterfly colonies in Mexico only occupied about 2.2 acres, about half of what they occupied the year before. This year, researchers in California counted just over 9,000 butterflies — the second-lowest amount since tracking began in 1997.
In December, the U.S. Fish and Wildlife Service announced that it’s considering protections for monarchs under the Endangered Species Act. Their threats include habitat loss, pesticides and climate change.
As a result, the agency said, the western migratory population has a 99% chance of extinction by 2080. It suggested several areas in California for critical habitat designations.
Hershcovich’s team in Colorado is stepping in to help the larger, eastern-based migratory population. The Butterfly Pavilion's partnership with the Government of Mexico is an initiative that aims to plant 100,000 native oyamel fir trees, which shelter butterflies in central Mexico all winter.
While the insects face threats along their migratory route, Hershcovich said, protecting their winter shelter is especially crucial. Less than 5% of the oyamel forests in Mexico remain.
“This is it – this is the home that they go to for the winter,” she said. “Should they lose those forests, the migration might collapse. It's such an important kind of piece of the monarch puzzle.”
The conservation effort, which starts this summer, will focus on planting trees at higher elevations in mountain forests, where the hope is that they can withstand climate warming. The project will also involve local schools in Mexico in the planting of gardens to attract the pollinators.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
