Biologists found just one monarch butterfly at Ellwood Mesa on Monday during the last butterfly count of the 2025-26 overwintering season. 

That follows the trend of declining numbers that biologists have observed for decades. Since the 1980s, there has been a 95% decline in the western monarch population. 

“It is always a treasure to see even one monarch’s bright wings fluttering by in the forest,” said Charis van der Heide, senior biologist and monarch butterfly specialist with Althouse and Meade Inc.

Contracted biologists with the City of Goleta, such as van der Heide, have visited various Ellwood sites since October to count the number of overwintering butterflies.

The count begins in October because that is when monarch butterflies typically migrate to Goleta and other areas on the California coast and settle into a habitat in an effort to stay safe against winter conditions. The butterflies then leave the area around mid-March.

The butterflies in the Goleta area seem to have already left for spring migration, according to the tiny trackers that biologists placed on the butterflies this past winter. 

The trackers allow not only biologists but community members to track the butterflies via bluetooth technology through the app Project Monarch Science.

Since the beginning of the overwintering season, van der Heide predicted that Goleta would see a low number of butterflies. 

“Like last year, the number of overwintering monarchs is much lower than the 10-year average,” she said.

For this year’s overwintering count, biologists had been scheduled to visit the sites biweekly but because of the low numbers, the frequency of counting days declined. 

A number of factors have historically threatened the monarch butterfly population, such as the loss of milkweed habitat for breeding due to herbicide-resistant crops, pesticide use, climate change, and logging and development.

The previous count, in January, found only two butterflies at Ellwood East. 

Around the time of the previous count, the county had just been soaked by winter rain storms, which van der Heide said might have led to some butterfly deaths.  

She added that deaths could occur because the overwintering butterflies depend on large populations for a “safety in numbers strategy.” 

“While the low numbers this year are very sad to witness, we can find hope that the western population was able to rebound after the historically low numbers of 2020, and there is the possibility that they will rebound next season,” she said.

In 2024, biologists found only four butterflies at the Ellwood Main Butterfly Grove, the area’s largest wintering site.

Additionally, in 2024, the butterfly was proposed to be identified as a threatened species under the Endangered Species Act.

However, the U.S. Department of the Interior, which makes the decision whether to include the species on the list, has yet to make one, according to the Xerces Society for Invertebrate Conservation, a wildlife conservation nonprofit organization. The decision is listed as a long-term action.

“This is a disappointing development,” Xerces Society for Invertebrate Conservation staff said in an article posted to the nonprofit’s website. 

They believe a decision could be made as early as fall 2026.

For Goleta, the butterfly counts will be shared with the city and added to its long-term data to share with scientists studying monarch butterfly conservation, George Thomson, parks and open space manager, told Noozhawk in January. 

Van der Heide said community members can plant winter-flowering nectar plants to help sustain overwintering butterflies and native milkweed in the spring to help the spring migration and breeding season.