FORT SILL, Okla., June 9, 2016 -- When Joe Grzybowski, interns and other bird experts head out into the backcountry here, they have one little bird in mind. It is an endangered species that could throw a wrench into the Army's training mission, but which Fort Sill is required, by law, to protect.
This little bird is the black-capped vireo. Fortunately for the bird and the Army, the vireo tends to nest in the oak scrub found in rocky terrain where no howitzer dares to tread. In a sense, the very existence of Fort Sill may have contributed to the bird's preservation, since the area was protected from development, and prescribed and natural fires maintain its habitat.
But why let a little bird few people have ever heard of take precedence over national defense?
The 1970 National Environmental Policy Act (NEPA), according to the Environmental Protection Agency, exists "to assure all branches of government give proper consideration to the environment prior to undertaking any major federal action that significantly affects the environment."
In other words, NEPA mandates that Marine Corps Base Camp Pendleton, Calif. protects the desert tortoise rather than run over it with a tank. It requires Fort Polk, La., to protect the longleaf pine forest the red-cockaded woodpecker depends on for its survival. And it assures that Fort Hood, Texas and Fort Sill will maintain the pockets of native scrub oak habitat needed by the black-capped vireo.
None of this jeopardizes national defense. However, it does preserve this country's national heritage, one which has lost -- or nearly lost -- many iconic species of birds, fish and wildlife.
"The Endangered Species Act was created to preserve our natural heritage and to maintain biodiversity, which has been declining," said Grzybowski, whose work with the black-capped vireo is one of the resources used by the Cornell Lab of Ornithology. "We're using endangered species as a vehicle for maintaining some integrity in the ecosystems."
To do that, Grzybowski has worked with both Fort Sill and the adjacent Wichita Mountains Wildlife Refuge for three decades, first to determine how many breeding pairs were still in existence, then to figure how to get those populations to increase.
In the mid-1980s Grzybowski's team did a survey west-central Oklahoma, checking three dozen or so known locations based on historical records. They found only one where the bird was still breeding. (It migrates to Mexico's Pacific coast in winter.)
A few pairs were located on Fort Sill in 1987 and a more thorough search in the next two years found about five dozen pairs in the Wichita Mountains area. Only five were on Fort Sill. Now, thanks to the efforts to protect them, there are 600 to 700 nesting pairs on the post and around 4,300 pairs on the refuge.
Why is this little bird an endangered species? Habitat loss has a lot to do with it. And so does the brown-headed cowbird. The cowbird is a native species, but it has a unique way of raising its young.
It doesn't.
The female cowbird lays one egg in the nest of a songbird. When the chick hatches it out-competes the rightful occupants for food, and soon becomes the sole chick in the nest. The black-capped vireo is a favorite target. Unfortunately, a cowbird can lay 40 or more eggs in a season this way, far more than other birds can.
"The problem the vireos have relative to other birds is that their incubation times are almost 15 days, and cowbirds hatch in 10 or 11 days," said Grzybowski, "so they were hatching four to five days ahead of the vireos." He has photos that show newborn vireos that are the same size as the cowbird chick's head.
"So there was zero production from a nest," he said of the situation. "Some places we searched off the area were close to 100 percent parasitism."
So he developed a way to get rid of the cowbird in vireo habitat, and now their surveys rarely show cowbirds have co-opted the vireo nests. Cowbird trapping (with permits) on post is now handled by Kevin McCurdy, retired Fort Sill natural resources biologist working for contractor Gulf South Research Corp. Cages are baited with food and live cowbirds. When the bird goes through the funnel-shaped entrance, it can't find its way back out. The birds are either destroyed or given to raptor rehabilitation centers as food for hawks, eagles and owls. (See "MeadowLarking" column on Page B1 to learn more.)
The black-capped vireo requires the kind of oak-scrub habitat common in the Wichita Mountains, which includes Fort Sill. That habitat is a "fire ecology" that requires periodic fires to burn off invading red cedar and other vegetation. Oaks tend to recover from a normal wildfire, whereas the red cedar is destroyed.
However, decades of a policy of fire suppression, as well as human development, have changed the habitat. The refuge and Fort Sill do prescribed burns to mimic the lightning-induced fires that were common here.
"The same kinds of things that could be done by maintaining habitat for black-capped vireos are also fire management strategies that protect property," said Grzybowski. Fire suppression increases dead wood and organic matter that will burn much hotter and become more destructive than in a habitat that tends to burn regularly, he said.
Fire managers nationwide have come to realize that, and wildfires are managed differently now. Fort Sill burns prairie and scrub to facilitate training, and to keep down the potential for wildfires from ammunition impacts. What's good for the mission, in this case, is good for the ecology.
For a bird that now nests only in parts of Texas, Oklahoma and northern Mexico, these cooperative efforts between federal agencies show preserving a little bird needn't jeopardize military training. This small part of America's natural heritage will continue to thrive as long as there are people like Joe Grzybowski and natural resources personnel here to make sure it does.
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