Clusters of Monarchs

Monarch numbers are rising at overwintering sites in Mexico and California. Catch up on the latest news from Estela Romero and Gail Morris. Stay tuned as monitoring monarch activity along the Southeastern region of the U.S. ramps up and news from the Monarch Butterfly Biosphere Reserve continues during the winter months.

The Leading Edge of Migration

Monarchs continue to arrive at the sanctuaries within the Monarch Butterfly Biosphere Reserve and migratory activity remains high farther north in Mexico as more monarchs are on their way.

Armando in Tula, TAM: "Continúan pasando muchas monarcas por Tula, Tamaulipas. Día soleado y fresco." [Translation: “Many monarchs continue to pass through Tula, Tamaulipas. Sunny and cool day.”] (11/14/2021)

Out West in California, the news remains hopeful as monarch numbers continue to grow. Over the past week, Journey North volunteers are reporting more fall roosts as monarchs head toward the coast.

Linda in Santa Monica, CA: "Ocean View Park in Santa Monica. For the last couple of weeks adult monarchs have been present in good number. Some have been roosting in a pine tree above the tennis courts. Hard to estimate total number in the area." (11/10/2021)

Leslie in Huntington Beach, CA: "The roosts have moved from Gibbs park to central park in front of the wooden amphitheater across the walkway . . . Mild weather, monarchs in eucalyptus trees." (11/10/2021)

Letter From Estela Romero: The Overwintering Season Begins

At El Rosario and Sierra Chincua sanctuaries, Estela Romero shares news of monarchs forming colonies as the overwintering season begins. Estela writes, "Today, as you can see from the photos taken at the El Rosario Sanctuary, monarchs are beginning to concentrate in high density . . . We are grateful to witness this extraordinary phenomenon and to be stewards of the monarch ancestral home here at the Reserve. This season, as in every winter season, the monarch behavior will unfold differently, bringing surprises. I look forward to describing these behaviors in these articles."

Leer más de la carta de Estela Romero: Comienza la Fase de Hibernación (versión en Español)»

Eastern Monarch Population

Eastern Monarch Fall 2021 Report #10

Activity remained high north of the sanctuaries in Mexico and Texas as more monarchs approached overwintering grounds. Along the Eastern Flyway, migratory monarchs were observed in the Mid-Atlantic, Southeast, and Gulf Coast regions. And surprisingly, a monarch was spotted as far north as Canada. Will this individual make it to Mexico?

Western Monarch Population

Letter from Gail Morris: Western Monarch Fall 2021 Report #10

Out west, Gail Morris shares more good news of growing monarch numbers in California. Gail writes, "The news is good in California! Unofficial counts totaling over 50,000 monarchs are appearing along the California coastal overwintering sites this week. After last year’s frightening drop to under 2,000 monarchs during the annual Thanksgiving count, everyone is excited by the appearance of so many unexpected monarchs. But monarchs are also appearing as singletons across the deserts of the Southwest, an annual trend as the season progresses. Soon monarchs will lose their urge to migrate and settle where they are for the winter."

One More Week of Fall Migration Updates

One week left for publishing our Fall Migration News Updates — but monitoring monarch activity and news from overwintering sites continues during winter. Stay tuned for updates via our website, social media, and email throughout December, January and February.