The area is comprised by tidal mud flats, salt marsh, brackish
marsh, and upland roosting sites. Bolivar Flats is actively
accreting due to the "North Jetty", constructed circa 1898 to
stabilize navigation channel into the Houston-Galveston port.
Since the lunar tide ranges are small (1-2feet), wind tides are
more important in flooding and draining Bolivar Flats. In winter,
strong north winds cause very low tides, and in summer, strong
southeast winds, especially tropical storms, cause tides well above
normal. The configuration of the site prevents excessive wave
action on the flats.
Approximately 140,000 shorebirds, representing 37 species use Bolivar Flats for both feeding and roosting. The area also serves as a year- round roost for gulls and terns; a feeding area for herons and egrets, a wintering site for the American White Pelican, and a wintering site for several species of waterfowl. The federally endangered species brown pelican and peregrine falcon are other important species using the flats for roosting and feeding. The adjacent salt marsh hosts clapper rails, seaside sparrow, and sharp-tailed sparrow. Black Skimmers and Least terns attempt to nest on the flats every year, but usually are not successful because of vehicular traffic. The huge bird population is largely supported by Bolivar Flats' rich, benthic infauna. Polychaet worms are the most abundant benthic animals.
Shorebird use is highest in the winter and in early spring. Dunlin, Western Sandpipers, Short-billed Dowitcher, and American Avocet are the most abundant winter shorebirds. Willets and Wilson's Plovers nest at the site. Willets, Black-bellied Plovers, and Sanderlings occur all year. The area is also one of the most important wintering sites for the threatened Piping Plover.
|Species||Annual Population||Species||Annual Population|
|Black-bellied Plover||2500||Lesser Golden Plover||100|
|American Avocet||20000||Snowy Plover||100|
|Lesser yellowlegs||1000||Wilson's Plover||750|
|Solitary Sandpiper||50||Semipalmated Plover||5000|
|Long-billed Curlew||750||Piping Plover||500|
|Ruddy Turnstone||2500||American Oystercatcher||100|
|Red Knot||1000||Black-necked Stilt||500|
|Semipalmated Sandpiper||1000||Western Sandpiper||50000|
|Stilt Sandpiper||250||Least Sandpiper||1000|
|Short Billed Dowitcher||5000||Dunlin||25000|
The area is managed as a shorebird sanctuary by the Houston Audubon Society. There is some recreational use by visitors to nearby beaches.Threats:
Vehicular traffic and loose animals are primary causes of disturbance in the area, threatening both birds and their eggs. The site's close proximity to Bolivar roads and the Houston Ship Channel creates great potential for oil spills in the area. Another threat is posed by fishermen who have requested that the slough next to the marsh be dredged. A dispute could arise in the future since the U.S. Army Corps of Engineers has considered the area as a source of sand in the past. The area is also actively accreting and is close to a highly urbanized area, thus there is the potential for future development.Ownership:
Bolivar Flats Shorebird Sanctuary is owned by the State of Texas. Under the jurisdictional authority of the Texas General Land Office, Bolivar Flats has been leased to the Houston Audubon Society for protection as a shorebird sanctuary.
Management and Research Activities:
A management plan will soon be prepared for the area. this plan will lay out future management activities for the area including: oil spill avoidance and contingency planning, piping plover recovery and research, restriction of vehicular traffic, protection of nesting birds, and public education.
Ted Eubanks has been banding and conducting studies of piping plovers in the area for the International Shorebird Survey.
Houston Audubon is trying to raise enough money to build a more substantial fence to restrict vehicular traffic in the area. They also have plans to construct educational signs and a viewing platform.