Quick Take
Santa Cruz County is updating its monarch butterfly habitat plan at Moran Lake, using new science to guide safe tree trimming that preserves critical overwintering habitat, writes Jeff Gaffney, director of the Santa Cruz County Parks Department. A recent wind study showed that work can reduce hazards without harming butterflies. Long-term efforts include planting native trees and engaging the community in conservation.
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Every fall and winter, one of the most delicate, iconic, endangered visitors, the Western monarch butterfly, settles in the towering eucalyptus trees surrounding Moran Lake County Park. The Moran Lake overwintering population remains the third-largest in Santa Cruz County, behind the Natural Bridges State Beach and Lighthouse Field sites. But, the numbers of monarchs across the state is still dwindling.
The monarchs cluster in the eucalyptus trees near the Lode Street sanitation facility and rely on the shelter of the grove to rest and survive the colder months. These butterflies are more than just a beautiful seasonal spectacle; they’re part of a fragile, threatened, declining population that depends on safe, wind-protected roosting habitat to complete their migration cycle.
Monarchs require specific microclimates: cool, moist and wind-sheltered coastal groves to survive the winter. Some challenges are the location of these coastal groves, which are found on private land, or public areas, like Moran Lake County Park, making their overwintering sites vulnerable to development, tree removal or unmanaged aging.
As stewards of Moran Lake County Park, Santa Cruz County Parks has been working closely with science-based organizations like the Xerces Society as well as the community to ensure we’re managing for both public safety and the butterflies’ overwintering habitat. In partnership with the Santa Cruz County Sanitation District and a consulting team of arborists, biologists and entomologists, we are updating the Moran Lake Monarch Butterfly Habitat Management Plan (MBMHP), which was first adopted in 2010, to reflect the latest science and best practices from monarch conservation experts, including the Xerces Society.
MORE ON MONARCHS: Read Lookout’s previous news and Community Voices opinion coverage here
This plan update isn’t just about planting trees or removing hazards; it’s about carefully balancing a delicate ecological landscape with the real-world needs of community safety, climate adaptation and long-term sustainability. Even modest reductions in canopy height or gaps in the windbreak can lead to wind speeds exceeding monarch tolerance thresholds (about 5 mph on the ground), potentially forcing monarchs to abandon those sites.
Results of the wind study
In response to community questions raised during our July 2024 public meeting, we commissioned a comprehensive wind study earlier this year. This study, completed in April 2025, analyzed how the current tree canopy protects the monarch cluster zones from wind, and how various tree management strategies would affect the monarch butterfly population.
The findings were encouraging, as we concluded that we can safely reduce the height of eucalyptus trees in specific zones around the lake without disrupting the overwintering habitat that monarchs rely on. The study helped us identify specific groves where we can trim trees to reduce the risk of tree failure and improve public safety without compromising the delicate butterfly habitat.
Summer 2025
Based on those findings, county parks moved forward this summer with tree work in the north and south Moran lakeside areas (referred to as areas B and C in the plan), as well as completed the removal of trees at the 40 Moran Way parcel (area A1). These areas were selected because of their proximity to recent tree failures, coupled with arborist recommendations.
Lewis Tree Service did the work under a contract approved by the county board of supervisors in May and amended in June 2025. As part of the restoration plan for this area, we will plant native trees, including Monterey cypress and white alder, there after the winter rainy season.
Phased progress, long-term vision
Several members of the community have asked about other parts of the park, such as the Placer Street windbreak. The sanitation district trimmed many of the trees in that area in 2024 and additional work is currently not included in this summer’s phase. However, the trees will be inspected for safety until we can undertake height reduction.
We’re taking a phased approach, prioritizing areas based on science, safety and environment. Our long-term goal is to gradually replace non-native blue gum eucalyptus trees with native species over the course of many years. These trees support monarchs, enhance riparian habitat, promote biodiversity and are more appropriate for the community and the monarch habitat.
In December 2024, we began this transition; community volunteers helped us plant 64 native trees in high-priority planting zones, and we will plant more this fall and winter.
We’re proud of the adaptive management practices we have incorporated into the stewardship of Moran Lake County Park. We are balancing the careful, science-based work which supports the critical monarch habitat, while simultaneously working with our engaged and passionate community.
We are grateful for our community’s ongoing help and advocacy to shape the park’s future as we work to protect this rare and valuable natural resource.
Jeff Gaffney has served as the director of the Santa Cruz County Parks Department since 2015. Since joining Santa Cruz County, Jeff has led major park improvements, expanded equitable access to recreation, developed a robust natural resource planning effort and overseen wildfire recovery efforts in impacted parklands. He continues to build partnerships throughout Santa Cruz County, seeking long-term, collaborative solutions.