In the 1970s I was employed in land saving as western regional director of the Nature Conservancy. One method that I advocated at the time was to acquire and reflood former San Francisco Bay wetlands. Now I realize that strategy lacked an important dimension: it failed to take into account the grassland habitat that would be destroyed in the process. As a result, one of my favorite birds, the burrowing owl (Athene cunicularia), has all but vanished from some areas around the Bay. What I learned from that experience leads me to suggest that as we continue the important work of restoring Bay wetlands, some of the land we acquire for this purpose be left dry.

One of the areas I viewed back then as a priority for tidal wetland restoration, Tubbs Island, belonged to a hunting club where I once had hunted. It had been artificially severed from tidal action. Left as dry weed fields with a small freshwater pond, it swarmed with diverse species of hawks and songbirds. Our effort to return the land to marsh was successful. Today the area is mostly a saltwater lake near the juncture of highways 37 and 121 south of Napa and westerly to the Bay. Much of the success of my effort to raise funds for nonprofit purchase of the area for this restoration project was due to the burrowing owl. I would simply drive with potential donors to the site and along the levee road. Pocking the levee were owl holes, beside which the little birds stood like vigilant sentries. I would stop the car a few yards from a burrow and we would watch. Anyone who cared at all about nature fell in love with the miniature owls, and large financial gifts often came our way as a result.

I was stunned, therefore, to learn recently that the owls are gone from the area. After a walk there, studying their absence, I concluded that we had been short-sighted 30-some years ago in our conviction that we had to return those hayfields to wetlands. Although draining the historic marshes for agriculture had created dry land artificially, we overlooked the fact that a new habitat had been created in the process, habitat that was now home to all kinds of organisms—hawks and wintering flocks of meadowlarks and nesting songbirds, not to mention the little burrowing owls.

Although I’m a trained biologist, I’d forgotten that diversity of habitat is the key to species preservation. Now I believe that our policy of total reflooding was in error; it was too simple a solution for a complex problem. In essence, the land reclamation that had gone on at mid-century had created a rare habitat, a sort of island within thousands of acres of salt marsh. To flood it was bound to change the ability of land-based species to live there—species that had found a safe haven there as housing developments crowded them out of nearby grasslands. Certainly, it appears to have nearly eradicated burrowing owls from much of the edge of San Francisco Bay. Had we left even 10 percent of those lands dry, in my opinion we could have saved the owls and other resident dry-land refugees. That small amount of dry land would, I believe, have provided enough habitat for the birds to hunt in. Given that one of the principles guiding Bay restoration goals was that plans should be modified to reflect improved scientific understanding and practical experience, I hope that in the future, restoration practices will be adjusted to ease the plight of the burrowing owl.

HUEY D. JOHNSON was western regional director of the Nature Conservancy, founded and ran the Trust for Public Land, was Secretary of the Resources Agency for Governor Jerry Brown, and currently is president of Defense of Place, an arm of Resources Renewal Institute. See http://HDJ.rri.org.

A MESSAGE FROM THE BURROWING OWL
Lynne Trulio

I share Huey Johnson’s deep concern that humans are driving burrowing owls to extinction in our state. He is right that human actions are responsible for the fact that owl numbers dropped by about 50 percent in the 10 years from the early 1980s to the early 1990s in California. However, wetland restoration projects are not the culprits.

The major blame for owl population losses, at least in urban areas around the San Francisco Bay, is rampant development and inadequate protection of species or their habitats. Burrowing owl populations plummeted as their open grassland habitat was paved over for huge commercial developments, subdivisions, and highways. Fewer than 10 percent of the state’s owls live on protected land, and no specific law stops the destruction of owl habitat. A recent petition by the Santa Clara Valley Audubon Society, the Center for Biological Diversity, and other organizations to list the burrowing owl as threatened in California would have provided essential protection. Unfortunately, the Fish and Game Commission turned down the petition, despite a recommendation from Department of Fish and Game staff that the bird be listed. Continuing urban growth puts the burrowing owl in peril.

But this said, Mr. Johnson has learned a very important lesson from the burrowing owl: positive actions such as restoring native habitats can have negative consequences, such as destroying habitat for other native species. This fact by no means diminishes the critical need and value of tidal restoration. It simply points to a need to think more broadly about the cascade of consequences these restoration projects entail. Because about 90 percent of California’s wetlands have been destroyed, many wetland-dependent species are now endangered. However, a number of native species, including the burrowing owl, have adapted to the landscape created by the diking and filling of baylands for agriculture and other human uses. Therefore, every restoration project must include protection of sensitive species that live on the land that will undergo restoration.

In the South Bay Salt Pond Restoration Project, a huge restoration effort now in the planning stage, habitat restoration includes protection for species using the current landscape. This 15,000-acre ecosystem project will help a number of rare species, including the California clapper rail and salt marsh harvest mouse, by restoring tidal marsh habitat that was lost when salt marshes were converted to ponds for salt production. However, because many species have adapted to salt pond habitats, including a number of resident and migratory bird species, tidal marsh restoration will be balanced with pond management. In addition, for the burrowing owl and other species that require high marsh and grassland habitat, wetland-upland transition zones will be included whenever possible. We have learned that, while restoration can bring back species that have lost their habitats, we must also use the restoration process to protect the species that are here now.

LYNNE TRULIO is an associate professor and is chair of the Department of Environmental Studies at San Jose State University. She is also the Lead Scientist for the South Bay Salt Pond Restoration Project. She has studied the ecology of burrowing owls and the restoration of wetland habitats in the Bay Area since 1988.

CORE HABITAT DESTROYED
Jules Evens

Burrowing owls are primarily birds of arid grasslands, especially low-lying, open prairie or shrub-steppe in California’s inland areas. They commonly associate with ground squirrel colonies, nesting in abandoned burrows. Among the most charismatic of California birds, the burrowing owl sadly has declined dramatically over the last 50 years, coincident with the conversion of the Great Central Valley grasslands and the arid foothills to urban environments. A statewide study by the Institute of Bird Populations found that nearly 60 percent of the breeding groups of owls known to have existed during the 1980s had disappeared by the early 1990s. Primary threats include habitat loss from land conversions for agricultural and urban development and the concurrent loss of ground squirrel colonies on which owls depend for nesting burrows. Additional threats include habitat fragmentation, predation, illegal shooting, and pesticide contamination.

The owls have been virtually extirpated from coastal counties and reduced to a remnant in the Sacramento Valley; San Joaquin Valley numbers are somewhat more encouraging, and Imperial County remains a stonghold. However, as the core population is decimated, there are simply not enough owls reproducing to replenish whatever habitat remains.

The owl’s reliance on grassland prey species has a carryover to ongoing marshland restoration efforts in California. According to a 2000 report by Lynne Trulio, burrowing owl habitat could be increased simply by adding upland transition, or “buffer,” zones between high marsh and lands converted to human uses. In other words, it is not wetland restoration per se, but failure to incorporate a buffer zone, coupled with a region-wide decline in the population that has led to the disappearance of these charismatic and engaging birds.

JULES EVENS is a wildlife biologist who works with Avocet Research Associates in Point Reyes.