Annual Monitoring Shows Sharp Decline in Monarch Overwintering Colonies in Mexico

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The Eastern migratory monarch butterfly is facing a serious threat: new reports reveal a significant population decline and a loss of habitat in the forests where they spend the winter each year. In just one year, the area occupied by monarch butterflies in their wintering habitat dropped 22%, from 7 acres to nearly 5.5 acres. This is part of a mostly downward trend over the past 25 years—when monarchs once covered more than 45 acres of forest.

Every year, Eastern monarch butterflies travel up to 2,800 miles from Canada and the US to their wintering sites in the forests of Mexico. There, in what is known as the Monarch Butterfly Biosphere Reserve, monarchs cluster in shelter from winds, rain, and low temperatures. Monarchs require a vast, healthy migratory path and large, robust forests for survival through the winter. Today, the butterflies face a reduction of breeding habitat in the US due to herbicide application and land use changes as well as forest degradation in wintering sites in Mexico. Extreme weather conditions in all these ecosystems can further their decline.

“It is not just about conserving a species, it’s also about conserving a unique migratory phenomenon in nature,” said WWF-Mexico’s General Director Jorge Rickards. “Monarchs contribute to healthy and diverse terrestrial ecosystems across North America as they carry pollen from one plant to another. With 80% of agricultural food production depending on pollinators like monarchs, when people help the species, we are also helping ourselves.”

The annual WWF-Mexico-led survey measures the area of forest in which monarch butterflies hibernate each winter, providing a scientific indicator of their population status. The 2022-2023 report shows a 22% decline in forest area when compared to last year. Another report found that 145 acres of forest have been degraded at the core zone of the Monarch Butterfly Biosphere Reserve, a major increase when compared to previous years.

Forest degradation impacts far more than butterflies. The Monarch Butterfly Biosphere Reserve not only provides monarchs with the right microclimate for hibernation but also serves as one of the main freshwater contributors for five million people in Mexico City and its metropolitan area.

How can we help protect this amazing species and its incredible journey? One way is by participating in community science projects that monitor and track monarch populations across North America. Community science (also known as citizen science) involves volunteers collecting data on natural phenomena such as wildlife sightings or plant distributions.

One example of such a project is eButterfly; allowing anyone to submit observations of butterflies from anywhere on Earth. By sharing your butterfly sightings with eButterfly, you are contributing valuable information that can help scientists understand how butterfly populations are changing over time and space.

eButterfly also helps you learn more about butterflies by providing identification guides, distribution maps, life history information, and photos of hundreds of species. You can also connect with other butterfly enthusiasts through forums and events.

By joining eButterfly or other community science projects related to monarchs (such as Mission Monarch, you are helping conserve these beautiful creatures and their habitats for future generations.

Read More about it here: Troubling news for monarch butterfly populations | Stories | WWF (