The fort also provides a haven for wintering bald eagles, visiting whooping cranes and peregrine falcons, and various plant and animal species. After the opinion was issued,, Fort Hood contracted with The Nature Conservancy of Texas to research and monitor the birds. The Nature Conservancy researchers teamed up with Fish and Wildlife Service and Army biologists to gather data on the two endangered species. The data they've collected constitutes the most comprehensive body of information on the birds. Mysteriously engineered by nature, migratory birds have relied for ages on built-in guidance systems to navigate long distances.
Some birds use the same nests they have occupied in previous years.
Vireos prefer nesting in patchy or clumped, scrubby vegetation whose leaf cover extends to the ground. Warblers build nests in mature oak-juniper woodlands, stripping the juniper bark for building materials. Critical nesting habitat of the black-capped vireo, an endangered songbird, is found on Fort Hood. Unfortunately, both vireo and warbler populations have been in decline for decades. Black-capped vireos, which once ranged as far north as central Kansas during the breeding season, are mostly confined to central and western Texas and northern Mexico.