Each winter, monarch butterflies west of the Rocky Mountains perform one of North America’s most remarkable migrations, traveling to hundreds of overwintering sites along the California coast and a handful of inland locations in California and Arizona. The Xerces Society recently released results from the Western Monarch Count (WMC), a community science effort that tallies monarchs at these overwintering sites. The results offer a mix of cautious encouragement and sobering reality.
The 2025 Western Monarch Count: The Numbers
Between November 15 and December 7, 2025, volunteers surveyed 249 known overwintering sites across the West. The mid-season count, which typically captures peak overwintering numbers, documented an estimated 12,260 monarch butterflies.
That total represents an increase from just over 9,000 monarchs last year, but it remains alarmingly low in a historical context. In fact:
- 2025 marks the third-lowest Western Monarch Count on record
- 2024 ranked as the second-lowest
- 2020 remains the all-time lowest count ever recorded
These recent results reveal perhaps the most striking pattern: three of the lowest counts in the program’s nearly 30-year history have occurred within the last five years.
A Steep Decline Over Time
The Western Monarch Count began in 1997, when early surveys estimated more than one million monarchs overwintering along the West Coast. Research conducted by Xerces Society partners suggests that western monarch populations were likely in the low millions during the 1980s.
Compared to those historical baselines, today’s numbers reflect a decline of more than 95 percent.
Importantly, this decline is not due to reduced monitoring. Volunteer participation and site coverage have increased steadily over time. In other words, we are counting more thoroughly and still finding far fewer butterflies.
Early Season vs. Mid-Season: A Late Arrival?
This year marked the second time Xerces Society conducted both an early season count and a mid-season count.
- Early season (Oct. 18–Nov. 2): ~6,000 monarchs across 218 sites
- Mid-season (Nov. 15–Dec. 7): 12,260 monarchs across 249 sites
That nearly 89% increase between early and mid-season counts suggests that many monarchs arrived later than expected. While it’s unclear exactly why, the increase offered some relief after early numbers raised serious concerns.
Still, even with that late-season bump, the overall population remains near historic lows.
Why Are Numbers Still So Low?
Xerces Society researchers point to several overlapping factors that likely contributed to this year’s results:
- Small starting population: Last winter’s near-record low meant fewer monarchs left overwintering sites to begin spring breeding.
- Poor to mediocre breeding season: Researchers from UC Davis reported some of the lowest breeding-season numbers they’ve seen in years.
- Ongoing drought conditions: While not the most severe drought on record, dry conditions in parts of the West likely reduced nectar availability for adult monarchs.
When populations start from such a low baseline, it takes a near-perfect alignment of weather, habitat, and resources to produce a strong rebound.
Stewardship Makes a Difference
While still a very important migration, Western Monarchs account for roughly 5% of the total North American migration. The vast majority of monarchs migrate through the Corn Belt. Also, following the historic low in 2020, monarch numbers rebounded sharply in 2021 when conditions aligned. That rebound demonstrated that monarchs can recover when landscapes provide what they need.
For Farmers for Monarchs, this moment reinforces a core truth: working lands matter. Pollinator habitat and milkweed availability, proper pesticide stewardship, and intact habitat corridors all influence whether monarch populations merely survive or have the chance to rebound.
As we look toward the coming growing seasons, the latest Western Monarch Count is both a warning and a motivation. The population is still dangerously small, but the pathway to recovery remains within reach, especially when farmers, ranchers, and land stewards are part of the solution.