The Army's Other Mission
Fort Hood is where soldiers train for war. It's also where two species of endangered songbirds nest.
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A tank passesd through black-capped vireo nesting habitat in Fort Hood, Texas. Photo courtesy of Gil Eckrich |
In the midst of exploding munitions and rumbling tanks, soldiers training at Fort Hood can hear something you wouldn’t expect at a military installation — the delicate songs of two endangered birds.
The 217,000-acre U.S. Army base northwest of Austin, Texas, doubles as the breeding ground for endangered golden-cheeked warblers and black-capped vireos.
Nearly 5,000 warblers and more than 8,000 vireos migrate from Central America and Mexico, respectively, to Fort Hood every March to breed.
Once at critically low levels, the two bird populations are now at carrying capacity, meaning their habitat cannot support any more birds, said Gil Eckrich, outreach coordinator for the Army Natural Resources Branch.
The black-capped vireos breeding at Fort Hood represent 80 percent of the known population, Eckrich added.
Besides training 43,000 soldiers, the Army at Fort Hood is also responsible for
protecting these endangered creatures.
Of the 1,200 species federally listed as threatened or endangered, 170 are found on U.S. Army land, according to the U.S. Environmental Center. In total, the Army owns 16.7 million acres of land.
It is in the Army’s best interest to preserve the base’s land and wildlife, according to Tom Green, Fort Hood project manager for The Nature Conservancy.
“The Army is mandated to sustain training lands, and natural landscapes are what they need to train in,” Green said.
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Golden-cheeked warblers were added to the endangered species list in 1990. Photo courtesy of Gil Eckrich. |
“Well-managed natural landscapes are much more resilient to the kinds of disturbances the Army causes than are artificial landscapes. The more natural processes that are functioning on lands, the more easily they can respond to vehicle traffic and the fires they set accidentally,” he added.
According to Eckrich, artillery rounds ignite these accidental fires. The blazes are critical for creating habitat.
The fires are especially important for black-capped vireos, which prefer scrubby oaks and grasslands — a habitat that needs fire to clear away unwanted undergrowth.
Landowners surrounding the base are not willing to allow wildfires or prescribed burns on their property. Consequently, Fort Hood has become an island of suitable warbler and vireo habitat.
Another reason the military post harbors such prime nesting habitat is because it has remained relatively intact since it opened in 1942.
“The No. 1 reason why wildlife habitat is being lost is because rural landscapes are being fragmented and because agriculture use can and often does adversely impact habitat that certain species need,” Eckrich said.
Suitable habitat does not exist in the civilian lands surrounding Fort Hood, Eckrich said.
Gary Amaon, Edwards Plateau ecoregional manager for the Nature Conservancy, said it is not uncommon for military posts to boast healthy ecosystems.
“Some of the best habitat for wildlife in the U.S. is on military bases,” Amaon said.
In addition to habitat loss, another bird was drastically reducing the endangered songbirds’ reproductive success.
Brown-headed cowbirds don’t make their own nests. Instead, they lay eggs in other birds’ nests and the young usually out-compete their hosts’ young.
“Population models said we would lose the vireo by 1995 if we didn’t stop the brown-headed cowbirds,” Eckrich said.
Consequently, The Nature Conservancy, a land-trust organization, began trapping and eliminating cowbirds from Fort Hood. More than 3,000 female cowbirds are trapped in 35 traps around Fort Hood each year.
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Black-capped vireos were listed as endangered in 1987. Photo courtesy of Chris Tesaglia-Hymes |
Eckrich said nest parasitism, which significantly affected the black-capped vireo population, has been reduced from 90.7 percent in 1987 to less than 10 percent for the past nine years.
The Nature Conservancy also helps the Army conduct prescribed burns to prevent wildfires and promote black-capped vireo habitat, Green said.
“Working on a military installation, we understand that the purpose is to provide military training. Within that context, we work with the Army to accomplish our objectives where they coincide with those of Army,” Green said.
As part of that partnership, signs restricting military training in endangered bird nesting areas were removed.
“We were so successful in managing the endangered species that they very rapidly expanded,” Eckrich said. “Before too long, if we were to protect all the habitat, we’d have a large portion of the installation closed or restricted for training purposes.”
A five-year study found no measurable difference in endangered species productivity between restricted and non-restricted areas on base, he said.
“The Nature Conservancy Fort Hood Field Office did the work and made the determination, and other agencies scrutinized the data. The U.S. Fish and Wildlife Service had to concur,” Eckrich said.
“We agreed we could protect both species without having signs up everywhere,” he said.
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