DNA Evidence Could Wipe Out Protection for California Gnatcatcher

By Cat Lazaroff

LAGUNA HILLS, California, September 28, 2000 (ENS) - A study challenging the uniqueness of a tiny southern California bird could delay indefinitely planned protections for the birdís habitat. The new report could also challenge the criteria by which species are listed as threatened or endangered in the United States.

New genetic data suggests that the threatened California gnatcatcher is so similar to its common Mexican cousins that no special measures - including the preservation of vanishing coastal scrublands - are necessary.

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The California gnatcatcher stands to lose habitat protection, and possibly threatened status, based on new DNA evidence (Photo by Arnold Small, courtesy USFWS)
California developers are using a report published in the October edition of "Conservation Biology" to argue that the U.S. Fish and Wildlife Service (USFWS) should delay its final determination of critical habitat for the gnatcatchers.

The agency is under a court ordered deadline to designate critical habitat for the California gnatcatcher by September 30. The USFWS has proposed protecting almost 800,000 acres for the tiny birds, one of the largest critical habitat designations ever made.

But scientists now say the small population of gnatcatchers in California may not need habitat protection, because they are essentially identical to the Mexican population, which is thriving.

Among the biologist authors of the new report is Jonathan Atwood, who reported a decade ago that the California and Mexican populations were distinct enough to be considered separate subspecies. That study was the primary evidence that the USFWS used in designating the California gnatcatcher as threatened under the Endangered Species Act.

Atwood and colleagues George Barrowclough, Rachelle Blackwell-Rago and Robert Zink used feathers plucked from gnatcatcher nestlings in California and Mexico to compare their DNA.

"Put simply, based on [DNA] data, northern populations do not appear to constitute a unique component of gnatcatcher biodiversity," the study concludes.

This new report could force a complete review of the proposed critical habitat for the California gnatcatcher.

It could also alter the manner in which species are determined to be sufficiently different from close cousins to be considered separate subspecies - and therefore worthy of separate consideration for threatened or endangered species status.

In a letter sent Monday to Interior Secretary Bruce Babbitt, California attorney Rob Thornton urges the secretary to delay critical habitat designation for the gnatcatcher. "It is hard to conceive of any new information that could be more significant and important than the new genetic data," wrote Thornton.

Thornton, who represents the Transportation Corridor Agencies, Pulte Homes Corporation and Forest Lawn Memorial Park Association in southern California, voiced the view of many developers in the region, who see the new gnatcatcher study as potential relief from restrictions on land use in the birdís habitat.

The Coalition for Habitat Conservation, a developer funded group that says it supports large scale, multiple species habitat conservation planning, has also written to Secretary Babbitt asking for a delay in the critical habitat decision.

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The California gnatcatcher is darker colored than its Mexican cousins (Photo courtesy USFWS)
"Clearly, the designation of 800,000 acres of habitat no longer can be justified if there is no subspecies, and the species itself is not threatened with extinction," wrote Laer Pearce, executive director of the Coalition. The delay is warranted, Pearce wrote, even "putting aside questions regarding whether the gnatcatcher should be delisted given this information."

That is the crux of the problem - whether Californiaís few thousand gnatcatchers are less in need of protection if other, nearly identical gnatcatchers live just across the Mexican border.

Environmentalists and some other scientists say the two populations of the birds differ in appearance, with California gnatcatchers having darker feathers and more gray on their breasts and tails than the lighter colored Mexican birds, which live largely in Baja California.

Andrew Wetzler, an attorney with the Natural Resources Defense Council, says the study is "not very relevant" to whether the California gnatcatcher should be considered threatened. "The Endangered Species Act does not define species just on the basis of genetic information," said Wetzler. "Itís more flexible than that."

Many scientists also argue that species are defined less by genetics - after all, humans and chimpanzees differ by just one percent of their DNA - than by subtler cues like appearance, behavior and distribution.

Losing the potential designation of 800,000 acres of critical habitat would be far less of a risk to the California gnatcatcher than the loss of its threatened status. That status protects the birds themselves and their nests wherever they occur.

Already, without a critical habitat designation, the birds have halted several development projects in southern California. In July, a federal court issued a preliminary injunction against Granite Homes, Inc., forbidding any further vegetation clearing or construction on a housing development in Elsinore until the court could determine whether gnatcatchers seen on the site would be adversely impacted by the project.

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The California gnatcatcher favors coastal shrub habitat (Photo courtesy California Native Plant Society)
Patches of the coastal sage scrub the gnatcatchers prefer are selling for up to $3 million an acre in southern California, providing high stakes for developers to avoid critical habitat designation for the birds.

But "preservation of coastal sage scrub cannot be linked to maintaining the genetic diversity of ... California gnatcatcher populations, despite previous recognition of subspecies," say the authors of the "Conservation Biology" report.

"The species as a whole is not threatened," the authors report. "Our study ... illustrates the danger of focusing conservation efforts for threatened habitats on a single species."

The Coalition for Habitat Conservation says their goal is also to promote broad habitat protections that do not focus on a single species.

"Even if the gnatcatcher were delisted - and I donít know of anyone whoís thinking about attempting that - it would have little effect on the national leadership southern California anjoys in habitat conservation planning," said Pearce. "The conservation reserves we have created protect many species besides the gnatcatcher, and are critical to our ability to meet Californiaís housing needs since they simplify the approvals for projects built on non-reserve lands."

The significance of the gnatcatcher study, Pearce said, is that it lends credence to the arguments by the Coalition and others that the USFWS critical habitat designation process is flawed.

"Should the Service rule on September 30 that 800,000 acres are needed, they will show that they are content to continue to base their decisions on faulty science, not on valid conservation biology," said Pearce.