Tom Stehn monitored Whooping Cranes at the Aransas National Wildlife Refuge for 29 years, until he retired last year. He is widely known as the authority on the wintering flock, the only self-sustaining, natural population of Whooping Cranes in the universe. I wrote about these Whooping Cranes in my book 101 Ways to Help Birds, in the section about why conserving water is so critical for birds. Tom Stehn was the authority I quoted.
These Whooping Cranes breed in Wood Buffalo National Park in Alberta. They mate for life and usually raise a single chick each year. Even with massive work by the US Fish and Wildlife Service and Environment Canada, these wild birds never spread beyond their traditional breeding and wintering areas, because they learn their migration route from their parents.
Most years it’s not too hard to keep track of wintering Whooping Cranes with aerial censuses. Pairs and families stay pretty centered on their territories, feeding on blue crabs in the more marshy areas of the estuary. Blue crabs can’t survive when the water gets too salty, and this year’s drought in Texas is one of the worst on record. Without the fresh water supplied by the rivers that empty into the estuary, the crabs decline, and the cranes must search harder for food. Starvation may take some, but before they succumb, they tend to wander in search of food. Birds on territory know where all the hazards are. When they wander off these havens, they’re more likely to be killed by accidents or predators. A severe drought in 2008-09 led to the deaths of at least 23 cranes—over 8 percent of their entire population at the time.
Because of this year’s record-setting drought, people in Texas have been fighting over the limited water supplies. A coalition of environmentalists, businesses, and local governments called The Aransas Project is suing the state of Texas, contending that its regulation of water withdrawals from the San Antonio and Guadalupe Rivers is detrimental to the health of the bay, which is the economic lifeblood of the area. The suit claims that the water policy during that 2008 drought caused the deaths of endangered Whooping Cranes. The case is in federal court because it involves the federal Endangered Species Act. Establishing a violation of the act requires proof that an endangered animal was killed and that the defendant, in this case the State of Texas and their water management system, caused the death.
The case was heard last week in Corpus Christi. Both the Aransas Project and the state had wanted to subpoena Tom Stehn, but the US Fish and Wildlife Service has rules preventing employees from testifying. But because his work was central to the case, the judge issued a subpoena, and last Tuesday Tom Stehn appeared before the court. He said that probably more than 23 birds died in the 2008 drought, because he did not have an accurate count of the sub adults. Whooping Cranes that are one to four years old don’t defend a territory, and they can wander extensively around the bay. But he said his number was an accurate minimum. The judge said, “I don't know how on Earth you could figure out what is going on with an endangered species without doing it the way he is.” Attorneys on both sides had accidentally misstated Stehn’s name as Mr. Crane, and the judge herself said, “This is the only human on Earth who has been counting these birds annually in this area. He is ‘Mr. Crane.'”
She’s expected to make a ruling soon on whether the state must change its policy to allow more freshwater to remain in the San Antonio and Guadalupe Rivers. It’s not going to be easy to balance the needs of everyone. As the judge asked, “Do you take from the farmers to give to the whooping cranes?” Ultimately, all of us are going to have to be better about water conservation.