Early last December, Tom Stehn was enjoying his retirement in Aransas Pass, soaking in his hot tub after a morning of windsurfing, when the phone rang. He grimaced for a moment but hopped out of the water naked to see who was bothering him. A U.S. marshal was calling from his car, which was parked in Stehn’s driveway. A federal judge in Corpus Christi wanted him to testify about the deaths of 23 whooping cranes he’d reported during the winter of 2008 to 2009, two years before he had retired. The marshal asked if Stehn could come to court immediately. “All right,” he said, “but give me a minute to put on my clothes.”
Stehn knew what the case was about. A longtime biologist for the U.S. Fish and Wildlife Service, he had served as its whooping crane coordinator for over a decade. No one had more hands-on experience with the birds, which are among the most endangered in North America. He had flown on countless aerial surveys to identify the whooping cranes’ winter territories in the Aransas National Wildlife Refuge, studied their habitat, measured the salinity of their marshes, celebrated their return each year, nurtured their sick, and, when he could, recovered their dead. In the winter of 2008 an emaciated juvenile had died in his arms.
Over the years, Stehn had watched the flock grow from 71 to nearly 300 birds. But he determined that during the drought of 2008 and 2009, 8.5 percent of the wintering flock and nearly 45 percent of the first-year juveniles had died. The following year, coastal tourism businesses, environmentalists, and the O’Connor family of Victoria, who owns tens of thousands of acres near the Guadalupe River, formed a nonprofit group called the Aransas Project and sued the state. The organization claimed that, under the Endangered Species Act, the Texas Commission on Environmental Quality ( TCEQ) was responsible for the deaths of the cranes because it had failed to allow enough freshwater to flow from the Guadalupe River into San Antonio Bay, which adjoins the wildlife refuge.
The State of Texas, led by the Guadalupe–Blanco River Authority ( GBRA), countered that the lawsuit was based on pure speculation. Of the 23 birds that Stehn had reported dead, only 4 carcasses had been recovered. How could he prove the others had died? And even if they had, how could the environmentalists know that the deaths resulted from a lack of freshwater? Witnesses for the state contended that computer models proved the whooping cranes could survive perfectly well with very little freshwater. They even claimed that because of a special gland, whooping cranes might not need to drink freshwater at all.
The case has exposed a long-simmering battle between the two sides. Although state law directs the TCEQ to plan for freshwater inflows to keep Texas bays healthy and productive, environmentalists have been complaining for years that the agency has failed to live up to its responsibilities. In 2003, for example, a group of environmentalists had applied for water rights to protect wildlife in San Antonio Bay, and the TCEQ denied the request. The GBRA, in particular, has a great deal at stake. Its priorities are cities, farmers, and industry, and there are plans for several new power plants, including a proposed nuclear facility, to be built in the region. If the plaintiffs win, those projects could be put on hold.
Both parties had visited Stehn’s old office and obtained copies of his annual reports, and both had tried to recruit him as a paid expert witness. Though the Department of the Interior typically prohibits its biologists from testifying as expert witnesses,