Shamrock Island Preserve in Corpus Christi Bay is one of the most important colonial bird-nesting islands on the Texas coast. Nineteen bird species, including the state-threatened reddish egret and white-faced ibis, nest on the 110-acre island preserve each year.
Grassland plants and shrubs help stabilize the dunes and other substrates, slowing wind and water erosion. Seagrass meadows provide essential forage for redhead ducks and nursery, foraging and refuge areas for many estuarine fish and invertebrates. Terrestrial plant communities on the site provide habitat components (nest sites, food) and shelter many resident and migratory species.
Vegetation communities of conservation interest include: seaside little bluestem, gulfdune crowngrass, sea oats, bitter panicgrass, woody glasswort, saltwort, saltgrass dwarf-shrubland, shoalgrass and Texas stonecrop. In addition, sand brazos-mint, Crown coreopsis, Velvet spurge, Coastal Plains umbrella-sedge, Jones' nailwort and Indianola beakrush are also often found here.
The island includes quality beach habitat used by skimmers and four species of terns, including more than 8,000 pairs of royal terns in some years. Grassy flats harbor an estimated 6,000 pairs of laughing gulls. Brushy uplands provide nesting cover for great blue herons, little blue herons, tri-colored herons, black-crowned night herons, great egrets, snowy egrets, reddish egrets, white-faced ibis and roseate spoonbills.
Protecting the island from disturbance and trespassing during nesting season is our highest priority. When birds are disturbed by boaters or fishermen and leave their nest, eggs will overheat in less than 3 minutes. Marine and bay debris are other problems for the island's birds.
Since acquiring the Shamrock Island Preserve, The Nature Conservancy of Texas, working with conservation partners, has developed a long-term habitat restoration and protection program on the island. Objectives include shoreline protection and the creation and enhancement of bird nesting habitat.
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Gulf Coast Prairies and Marshes Ecoregion (PDF)
Access to the island is strictly prohibited during the February through August nesting season, unless prior arrangements are made with the state office of the Conservancy.