Despite Controversy, the Coastal California Gnatcatcher Will Remain an Endangered Subspecies

The fight to delist the bird hinged on disputed science鈥攖he same science behind an ongoing delisting petition for the Southwest Willow Flycatcher.

In late August, the U.S. Fish and Wildlife Service (USFWS) granted a reprieve to the coastal California Gnatcatcher, a tiny gray insectivore found in Southern California. Back in 2014, a group of builders associations with ties to the Pacific Legal Foundation submitted a petition to delist the bird, arguing that it isn鈥檛 a separate subspecies of California Gnatcatcher and therefore didn鈥檛 warrant protections under the Endangered Species Act. After more than a year of collecting evidence and listening to the recommendations of a panel of six independent experts who reviewed all the available scientific聽evidence, the USFWS declared that the coastal population is distinct enough from other California Gnatcatchers that it deserves to retain its protections under the Endangered Species Act.

The gnatcatcher wasn鈥檛 the only bird to face a delisting petition on account of its status as a subspecies, or even the only bird targeted by Pacific Legal Foundation and its partners. Still wending its way through the review process with the USFWS is a similar petition regarding the Southwest Willow Flycatcher. Both birds live in diminishing pockets of habitats: the gnatcatcher in coastal sage scrub, which has been highly fragmented by development, and the flycatcher in riparian corridors, 95 percent of which have disappeared due to land-use changes and drought. Life is particularly rough for the Southwestern Willow Flycatcher. This past聽year, 探花精选 scientists found only one of them on the 45,000-acre Kern River Preserve in California, an area that should be rich with the birds.

The basis of the reviews comes from two papers, published in 听补苍诲 , by Robert Zink, a conservation biologist at the University of Nebraska. Zink analyzed both the birds鈥 genomes and their ecological niches (basically, what kinds of habitats they use and how they use them) and concluded that the two subspecies were not different enough from the rest of California Gnatcatcherdom and Willow Flycatcherdom to warrant protections. His reasoning聽being聽that聽whatever genetic, ecological, or behavioral distinctness those populations have, losing them would not, in effect, be such a great loss.

Multiple scientists have taken issue with Zink鈥檚 conclusions. Tad Theimer of Northern Arizona University looked at how blunt an instrument the ecological niche modeling Zink used in his research聽can be. After running simulations, 聽that Zink鈥檚 methodology couldn鈥檛 differentiate between a flycatcher and a Yellow Warbler, let alone two flycatcher subspecies. , John McCormack of Occidental College examined both Zink鈥檚 niche modeling and his genetic analysis of the coastal California Gnatcatcher. He concluded that the data was insufficient to make a determination one way or another听补苍诲 flagged in particular Zink鈥檚 use of only a few select points on the gnatcatcher鈥檚 genome. McCormack argued that in order to make a definitive determination that the coastal California Gnatcatcher isn鈥檛 a subspecies, Zink should have looked at hundreds of spots on the bird鈥檚 genome. In both cases, scientists concluded that there simply wasn鈥檛 strong enough evidence to unequivocally declare that the disputed populations weren鈥檛 subspecies.

Zink is a well-regarded scientist. His peers have spoken highly of the quality of his past work, even when they completely disagree with the conclusions he drew regarding the flycatcher and gnatcatcher. If it stopped there, this would be a relatively standard scientific argument鈥攖he type of which has been going on in academic journals for decades. But in the background of this debate lurks the California Building Industry Association, one of the groups on both delisting petitions, represented by its lawyer Robert Thornton. It did not go unnoted that Zink thanks an R. Thornton for financial assistance on his 2013 gnatcatcher paper鈥攖he very paper used as the basis for the subsequent delisting petition. Multiple scientists interviewed for this story brought up the troubling implications; ample scientific research has shown that funding can subconsciously bias the conclusions of researchers even though they believe themselves impartial.

In the end, the six independent scientists working with the USFWS seemed to agree with the assessments of McCormack, ,聽鈥淎mong the primary weaknesses of the research conducted by Zink et al. 2013 were the selection of genetic markers and lack of hypothesis testing. Specifically, the type of loci and analyses were not suited to identifying recent, intraspecific divergence.鈥 With the聽Southwest聽Willow Flycatcher's聽fate聽still being determined, conservationists hope聽that the USFW聽will find the same faults with Zink's flycatcher research听补苍诲 deliver a similar rejection. But even when the final decision does get made, it will only take another bit of research to bring about another delisting petition. With so much potential money to be made, this isn't likely the last of these challenges we'll see.