Monarch butterfly (western migratory population)

How it was counted

The Xerces Society's Western Monarch Count adds up the monarchs seen at wintering sites in groves on the California coast, at the height of the wintering season. Only butterflies at the sites counted are in the number, so it is a floor and not an estimate of the whole. The count before it, 9,119 in 2024, was lower; Xerces still reads both as part of a long decline.

This is a minimum, not an estimate of the total: the monarchs actually seen at the wintering sites that were counted.

Earlier figures

• 9,119 in 2024: the previous count. Source: Xerces Society for Invertebrate Conservation (Western Monarch Count).

What moves it

The Xerces Society names the loss of winter groves on California's coast to development as a major pressure, and ties the long decline to shrinking habitat, pesticides and a changing climate.

• loss of overwintering groves on the California coast to development. Source: Xerces Society for Invertebrate Conservation (Western Monarch Count).
• habitat loss, pesticides and climate change behind the long decline. Source: Xerces Society for Invertebrate Conservation (Western Monarch Count).

The next count

The count is annual. No date for the next count is known as of 12 November 2026.

Sources

• Xerces Society for Invertebrate Conservation (Western Monarch Count) Last checked 12 November 2026.

What changed

• 12 November 2026 Added to Live Species, counted another way: 12,260 (Butterflies counted at winter sites, a minimum, December 2025).
• 13 November 2026 A line of the record's wording changed.

Every change on the site