HOUSTON (AP) — The whooping crane is North America's tallest bird, standing 5 feet with a wingspan as wide as a pickup. There are not many left, and the last migrating flock in the wild returns each winter to the same marshy flats on the Texas coast.
So one might think it should be easy to count every whooper, as they are affectionately known, while they are here, but it's not.
After six decades of trying, the U.S. Fish and Wildlife Service is proposing a new way to survey the iconic bird, replacing a frequent count with science-based estimates that federal biologists say provide a more realistic view of the endangered population.
The Fish and Wildlife Service, in a trial run, estimated 254 cranes were present at the Aransas refuge last January, but acknowledged the flock's size could be anywhere between 199 and 325 birds.
The proposed change has riled bird lovers and the businesses that cater to them in the small towns near the Aransas National Wildlife Refuge, 170 miles southwest of Houston. They worry the wide range in population estimates could adversely affect recovery efforts.
"It is not a real count," said Ron Outen, a retired Environmental Protection Agency administrator who lives near the refuge in Rockport. "Maybe there were 254 birds out there. Maybe there were 230. Maybe there were 270. It's all within the range, but when there are less than 300 birds, a handful of birds matters."
Protecting the species, which is slowly making its way back from the brink of extinction, is an urgent theme in Rockport and Fulton, coastal towns that have capitalized on the booming interest in the majestic crane.
The flock, which represents about half the whooping cranes on Earth, migrate 2,400 miles each fall from its breeding grounds in Canada to the Aransas refuge.
After 23 whooping cranes died in the winter of 2008 and 2009, bird lovers, businesses and some municipalities formed the Aransas Project and sued Texas. The group, led by Outen, claimed the state caused the deaths by diverting too much water from Guadalupe River before it reached the birds' feeding grounds.
A ruling from a federal judge in Corpus Christi is expected as soon as next month, and it may hinge on the quality of data of Tom Stehn, a longtime Fish and Wildlife Service biologist who counted the cranes at the Aransas refuge for 29 years. He retired last year.
The Fish and Wildlife Service has since found fault with his decades-old methods, suggesting they wrongly assumed birds missing from their territories had died.
The new technique, which is widely used to determine populations of rare and endangered wildlife, has a more rigid protocol for aerial surveys and the identification of cranes. For example, the flights will be conducted at the same speed and altitude during the same time of day to avoid low sun angles that make them more difficult to spot.
"The big advantage of the new method is that it can repeated," said Brad Strobel, a Fish and Wildlife Service biologist based at Aransas. "It does not rely on any specific observer or knowledge."
Stehn said he believed his census was 98 percent accurate, but conceded he could not prove it. Still, the new method uses a wider, less reliable flight grid during aerial surveys and does not determine mortality or identify the location of the whoopers' territories, he said.
Stehn said it would be possible to count every whooping crane until the flock exceeds 500 birds, in part because almost all of the birds winter in a well-defined and finite area.
Todd Votteler, who oversees science and policy for the Guadalupe-Blanco River Authority, said the new method is better because the birds do not always go where expected. Last winter, whooping cranes were found outside the refuge, including sightings in Central Texas, Kansas and Nebraska, because of food shortages and drought.
"Clearly, this is saying you cannot do an exact numeration," Votteler said of the new survey method. "You can get an estimation within a range. It's more realistic.
"The problem is, people are so used to hearing an exact number."
Information from: Houston Chronicle, http://www.houstonchronicle.com