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Bird Friendly Base

Endangered Species Bounce Back at the Army’s Fort Hood

by Christine Mlot

Fort Hood, Texas, is home to the U.S. Army’s biggest collection of tanks and other heavy military hardware. It is also home to one of the largest expanses of habitat for two species of endangered birds: the black-capped vireo and golden-cheeked warbler, songbirds that have flourished in recent years amid the din and destruction of field exercises and tank training. “We’ve got a stunning number of birds out there,” says John Cornelius, chief of natural resources at the base.

In 1987, when the black-capped vireo was first listed as endangered, Cornelius counted fewer than 100 of the birds on the base. When the golden-cheeked warbler was listed as endangered in 1990, the Army restricted operations on all habitat at the base: During nesting season, nearly a third of Fort Hood was off-limits for training.

In 1997, the Army started working with The Nature Conservancy to help foster the recovery of the migratory birds. One goal was to increase the vireo population to 750 breeding pairs. “We’ve totally blown that away,” says Richard Kostecke, a Conservancy scientist. By 2003, surveys recorded more than 1,800 vireo pairs, according to a paper published last year. Kostecke says 2005 surveys turned up an estimated 5,000 pairs. Similarly, the golden-cheeked warbler has burgeoned to an estimated 4,600 pairs from approximately 1,000 pairs in the early 1990s.

The key to the vireo’s recovery has been the trapping of brown-headed cowbirds, which lay their eggs in the nests of other birds, to the detriment of the songbirds’ own young. Named for their penchant for feeding on insects kicked up by cows and other livestock, cowbirds have flourished as farms have replaced eastern forests. In 1987, Cornelius found the parasitic cowbirds in more than 90 percent of vireo nests; now they occur in less than 10 percent. Research on the warbler is still in early stages, but scientists say cowbird suppression and habitat protections may have contributed to the increase in numbers.

Today, only 9,500 acres (4 percent) of the base are subject to habitat restrictions. “We’ve demonstrated that endangered species management and military training are not incompatible,” Cornelius says. The training can even be beneficial for certain species, says Gary Amaon, the Conservancy’s program manager for central Texas. Fires started by military explosives create the vireo’s favored open habitat, as does tank traffic. The net result, says Amaon, is that “the birds are doing better here than anywhere else in their range.”