In 1900, up to 1,000,000 Attwater's prairie-chickens inhabited the coastal grasslands. Since that time,
T. sebifera has proven to be an aggressive invader of the coastal grasslands, where it displaces the diverse native plant assemblage that was dominated by prairie grasses and
forbs with dense, near-monospecific stands that significantly alter biotic and abiotic ecosystem processes. Coastal prairies have also declined with the invasion of non-native grasses such as
Old World bluestems which create monocultures and change the structure of native grasslands. Urbanization has further contributed to habitat loss. As a result of these changes over the last 100 years, the grassland ecosystem where Attwater's prairie-chicken once thrived exists in small, scattered patches whose continued existence is threatened. Where once grazing
plains bison and periodic
wildfires due to lightning reduced brush, the birds now have difficulty making their way through thick undergrowth. Other, less-apparent changes in the ecosystem possibly have had an effect as well. A 1937 study recorded about 8,700 Attwater's prairie-chickens remaining in four Texas counties. Attwater's prairie-chicken has been on the
endangered species list since March 1967 when an estimated 1,070 birds were left in the wild. By 2003, fewer than 50 birds remained in the wild. In 1999,
The Nature Conservancy decided to permit new drilling close to primary breeding grounds on Texas land owned by the Conservancy. That harmed the prairie-chicken population at that location in the view of some organizations, including the
Wildlife Society. The number of Attwater's prairie-chickens nesting on the land owned by the Conservancy fell from 36 in 1998 to 16 in 2003. Abilene Zoo, and
Caldwell Zoo (Tyler, TX). Through a partnership with the
Houston Zoo, a captive-breeding flock is residing on the grounds of the
NASA Lyndon B. Johnson Space Center near
Clear Lake. In 2016, the population declined to 42 birds following heavy spring floods, which wiped out an entire generation of eggs.
Hurricane Harvey in 2017 was even more disastrous, likely killing at least 32 birds, with only five females found during the post-hurricane survey of the area. However, in the spring of 2018, the estimated wild population was 12. As of February 2019, with the Houston Zoo having released many individuals the previous year, the wild population was around 200. Since then, the wild population has decreased again. A count done later that year indicated only 108 birds remaining and a report from February 2021 stated fewer than 100. == In popular culture ==