Places We Protect

Shamrock Island Preserve


A variety of waterbirds sit on a sandy beach with thick, green brush in the background.
Shamrock Island Waterbirds flock to this colonial bird-nesting island. © Rich Kostecke

Shamrock Island Preserve is an important colonial bird-nesting island on the Texas coast.



On the eastern shore of Corpus Christi Bay lies one of the most important colonial bird-nesting islands on the Texas coast. The island was once an extensive peninsula of Mustang Island, but in the 1950s a series of navigational channels were dug into the landmass for oil and gas exploration, significantly weakening it. In early August of 1970, Hurricane Celia's path of destruction completely separated the peninsula into an island, creating a prime rookery nearly free of human disturbance and predatory wildlife. Today, it remains one of the most productive waterbird nesting islands on the Texas coast. Nineteen waterbird species now nest on The Nature Conservancy (TNC)'s 110-acre Shamrock Island Preserve each year, some of which have thousands of nesting pairs.

Grasses and shrubs help stabilize Shamrock Island's uplands, while marsh plants occupy areas frequently inundated with high tides. Seagrass meadows help reduce wave energy and provide essential forage for redhead ducks, as well as nursery, feeding and refuge areas for many estuarine fish and invertebrates. In addition, resident and migratory species depend on the preserve’s land-based plants for nesting sites, food and shelter. Among the plant communities of conservation interest are seaside little bluestem, gulfdune crowngrass, sea oats, shoal grass and Texas stonecrop. 




110 acres

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A bird chick with fuzzy feathers and an open beak.
HATCHED Each year, numerous chicks hatch on Shamrock Island Preserve, like this young Caspian tern. © Rich Kostecke

Why This Place Matters

Shamrock Island Preserve supports a number of rare bird species, such as the state-threatened reddish egret and white-faced ibis, as well as one of the largest colonies of nesting brown pelicans. The island also has quality beach habitat for ground-nesting birds such as skimmers and four species of terns, including more than 8,000 pairs of royal terns in some years. Grassy flats can harbor an estimated 6,000 pairs of laughing gulls, while brushy uplands provide nesting structure for many other waterbirds. These nesters include great, little blue and tricolored herons, as well as black-crowned night herons, great and snowy egrets and roseate spoonbills.

Conservation efforts have helped make Shamrock Island a leading site for colonial waterbirds with breakwaters being built to protect shorelines from excessive wave action. The preserve is also farther removed from land, keeping predators such as coyotes and feral hogs from reaching the island and helping nesters be more successful.

However, the island is unusual in that it lacks a submerged sandbar just offshore. During calmer days, gentle waves generally roll across a sandbar and replenish grains of sand pulled from beaches during storms or heavier waves. Without a sandbar, erosion can steal up to 14 feet of Shamrock Island’s shoreline in a year—and if left unchecked, this erosion could seriously reduce the island's size and beaches, putting the viability of nesting on the island at risk.

Photos from Shamrock Island Preserve

Discover the diverse wildlife at this critical colonial bird nesting island.

Three white birds with orange faces and long, slender beaks sit in green vegetation.
A pink feathered bird stands bent over in shallow, calm water with its spoon-like beak in the water.
At least 8 adult brown pelicans stand in the sand on the shore, wading into ocean waters.
Two volunteers crouch near the shore, planting small, green seedlings in the sand.
Two featherless, white baby pelicans huddle together in a nest amongst green vegetation
Two gray birds with white bellies stare off into the distance as they sit amongst green vegetation.
Two birds with brown bodies, white necks, brown crowns and orange beaks stand on a branch.
Over a dozen small white and black birds with bright orange beaks sit on nests in the sand.
Two white-colored reddish egrets sit at the top of green vegetation against a blue sky.
Five large, brown pelicans sit on low lying branches along the shore.
Five volunteers plant native seedlings on the beach.
RESTORING HABITAT Gulf Corps volunteers plant native species at Shamrock Island Preserve. © R.J. Hinkle

What TNC Is Doing

Since acquiring Shamrock Island Preserve, TNC and its conservation partners have developed a long-term habitat restoration and protection program here. Much of this work hinges on the installation of 30 breakwaters just offshore, which is meant to provide a first line of defense against shoreline erosion.

The reinforced rock walls slow waves as they roll in, allowing sediment to fall from the water and settle. In addition to helping replenish sand, the protective rock walls create excellent conditions for the establishment of seagrass habitat. That seagrass helps anchor sand and sediment to the bay bottom, an additional step in baffling waves closer to shore. Future work includes breach repair of the island's shoreline and shrub restoration as a result of large-scale impacts from Winter Storm Uri in 2021.

Moreover, protecting the island from disturbance and trespassing during nesting season is one of TNC's highest priorities. When nesting birds are disturbed by visitors on the island—which causes them to leave their nests—eggs can overheat in less than three minutes. Chicks are also vulnerable to predation by laughing gulls or other predatory birds. Enhancing nesting habitat and addressing marine and bay debris, which occasionally wash up on shore, are also helping ensure the survival of the many bird species that make Shamrock Island their home.

Learn More

Shamrock Island Preserve is always closed to the public. Waters surrounding the island are open to the public for recreation, but we ask that you “Fish, Swim and Play from 50 Yards Away” to give space for waterbirds.

Access to the island is strictly prohibited during the February through September waterbird nesting season, unless prior arrangements are made with TNC. For more information, contact Director of Landscape Initiatives Sonia Nájera (snajera@TNC.ORG).