Home News Monarch Butterflies, Loved Across Mexico, Make a Surprise Early Return

Monarch Butterflies, Loved Across Mexico, Make a Surprise Early Return

Monarch Butterflies, Loved Across Mexico, Make a Surprise Early Return

The first monarch butterflies (Danaus plexippus) have begun crossing the border between the United States and Mexico as part of their annual migration to the hibernation sanctuaries in Michoacán and the State of Mexico. This journey was reported by the citizen science initiative, Correo Real, as the butterflies moved through the La Amistad International Reservoir, which straddles the Río Bravo and divides Del Río, Texas, from Ciudad Acuña, Coahuila. 

Mexico Rejoices at Sight of Beloved Butterflies

On Wednesday, October 2, Correo Real observer Roberto Enríquez reported from the reservoir that monarchs were arriving in Mexico, with an estimated flow of 15 to 20 butterflies per minute after midday. In a video recorded from the site, Enríquez noted as per Milenio, “We are at the La Amistad International Reservoir, where the U.S. ends and Mexico begins. We’re witnessing the arrival of the monarch butterfly; there goes one flying, crossing the reservoir and entering Ciudad Acuña, Coahuila, into Mexico.” 

Earlier, on October 1, another observer, Roberto Carlos Armendáriz, reported the presence of about 200-300 monarchs near Del Río, while Correo Real observer Nereida Barrios observed 20 monarchs perched in the Braulio Fernández Park in Ciudad Acuña by 7:00 p.m. 

Rocío Treviño, coordinator of the Correo Real initiative, expressed surprise at the early arrival of the monarchs. “In recent years, the monarchs have entered Mexico later in the season, usually around mid-October,” she explained. However, this year, observers have noted the presence of one to three butterflies since the end of September. The sighting of up to 20 butterflies per minute indicates a significant migratory flow already entering Mexico, with the butterflies expected to reach the hibernation sanctuaries by November 1 or 2. 

“This is an important signal that the monarchs are arriving,” Treviño added. “For several autumns, we haven’t seen this early entrance, but now they’ve come at the expected time. Last year, they didn’t arrive until October 13.” 

Observers in northern Mexico have begun reporting solo monarch sightings in Ciudad Acuña, Sabinas, and Monterrey’s metropolitan area. “Our Correo Real colleague, engineer Roberto Enríquez, informed us yesterday that there’s already a significant flow of butterflies — around 20 per minute — which is a positive sign,” Treviño said. She anticipates more sightings in the coming days. 

Why the Early Migration of Monarch Butterflies Matters

Despite this early arrival, the monarch population has faced a significant decline. During the 2023-2024 migration season, the monarchs’ occupation of their hibernation sanctuaries in Mexico dropped to the second-lowest level on record. The butterflies colonized just 0.90 hectares in Michoacán and the State of Mexico, representing a sharp 59.3 percent decrease. 

This decline has been attributed to global environmental factors, as outlined by Gloria Tavera Alonso, Director General of Conservation at the National Commission of Natural Protected Areas (Conanp). “In the 2023-2024 season, the monarchs occupied a surface area of just 0.90 hectares, which is a significant drop. A decade ago, in the 2013-2014 season, we saw a similar decline to 0.67 hectares,” Tavera said during a press conference held in February. 

The monarchs’ early arrival in Mexico offers a glimmer of hope amid the broader environmental challenges they continue to face. 

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