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Habitat Restoration in Irvine Supports Threatened Species

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The coastal cactus wren builds its nests in patches of old-growth prickly pear cactus, providing itself protection from predators. However, recent fires and past land uses have eliminated most of the mature cactus, which in turn threatens local cactus wren populations.  

Organizations such as the non-profit Nature Reserve of Orange County, the City of Irvine and Irvine Ranch Conservancy are working together to expand the wren’s habitat, by connecting isolated patches of prickly pear cactus with each other to over time create a larger, contiguous habitat for the coastal cactus wren. 


But why go to all this effort? It’s just one bird, and one plant. Our local ecosystem is very biologically diverse, and species such as the coastal cactus wren are only found here. Each species in our local ecosystem plays an important part in making the whole stronger and more able to bounce back from threats such as fire, flood, drought, and climate change.

“If you think of a strong, bio-diverse ecosystem as a building and individual species as bricks, each brick you remove makes the building weaker,” says Michael O’Connell, executive director of Irvine Ranch Conservancy.  “If enough bricks disappear, the building crumbles. This is what happens in ecosystems too.”

Conservation of local open space areas are governed by the nation’s first Natural Community Conservation Plan, an agreement between regulatory agencies, local governments and land developers to protect and restore permanent native habitats in an entire region in exchange for development in other less sensitive areas. The plan helps preserve the land for both people and nature by directing human impacts on local flora and fauna to areas that are less critical.

The Conservancy works with landowners such as OC Parks and the City of Irvine and other partners to help them manage their lands and obligations under the Natural Community Conservation Plan, helping implement habitat restoration, creating resource-sensitive trails, and leading and monitoring public activities on the land.

One such project currently underway in the Shady Canyon area of Irvine is the Mule Deer Restoration Project, named for its proximity to the Mule Deer trail in the City of Irvine’s Open Space Preserve. Building on successful restoration projects nearby, the Conservancy is restoring more than two acres of habitat, including a number of cactus plantings. The area was grazed by cattle until the end of the last century, leaving non-native grasses and other weeds that inhibit re-growth of native plants.

The coastal cactus wren is not a strong flier, so young birds looking for their own place to live don’t really fly too far from the nest.  Patches of cactus have to be relatively close to each other for wrens to move among them. This restoration project is part of an overall plan for “habitat linkages,” which will eventually connect patches of existing coastal cactus wren habitat in the James Dilley Reserve off Laguna Canyon Road to these in Shady Canyon.

In addition to native grasses and shrubs, planting plans include 4,500 prickly pear cactus “pads” (oval flat segments of the cactus sometimes called “nopales”), along with 20 large, mature cactus plants to anchor the cactus islands By incorporating mature plants, the Conservancy hopes to encourage a faster return of coastal cactus wrens and nesting.

The project includes before-and-after monitoring of both the cactus patches and coastal cactus wren to track growth and population expansion. Along with Conservancy staff, the UC Irvine Center for Environmental Biology is also partnering in the project. A UCI scientist tests soil before planting and during the project to track changes, and environmental science students are participating in planting and data collection.

Members of the public are also welcome to join the project and help build the habitat linkage to support the coastal cactus wren and other rare native species. The Conservancy’s Science and Stewardship division has organized several planting activities through March, to take advantage of winter rains. The next public volunteer opportunities are February 2 and 8 from 9 a.m. to 12:30 p.m. Pre-registration is required to take part in these volunteer activities. To learn more about these activities or to register, visit www.LetsGoOutside.org/activities.